Hero of the Vosburgh Stakes (gr. I) and Jerome Handicap (gr. II), Girolamo is the only six furlong grade one winner by A.P. Indy. Out of a graded stakes winning daughter of Mr. Prospector, Girolamo is bred on an identical cross to Malibu Moon, Pulpit, Mineshaft and Congrats, and is also a brother to the dam of Super Saver and Bluegrass Cat.

Girolamo is out of a mare by Mr. Prospector, but there are seven other sires who are by A.P. Indy out of daughters of Mr. Prospector, and who have sired stakes winners out of Mr. Prospector line mares. Mr. Prospector line horses which are broodmare sires of stakes winners by A.P. Indy include Seeking the Gold (sire of Petionville, Mutakddim - who gives inbreeding to this family - and Cape Town), Machiavellian (sire of Street Cry), Kingmambo (whose son, Lemon Drop Kid, will give inbreeding to A.P. Indy and a three-parts-sister), Smart Strike, Gone West (and his sons, Grand Slam and Mr. Greeley), Forty Niner (and his sons Twining and End Sweep, with Distorted Humor, also looking promising), Gulch and his son Thunder Gulch (sire of Point Given), Afleet, Conquistador Cielo (sire of Marquetry, grandsire of Artax), Miswaki (and his son, Black Tie Affair), Unbridled's Song, Unbridled, Quiet American, Rubiano and Pentelicus (all from the Fappiano branch), Silver Ghost, and Distinctive Pro. Woodman, who is also a broodmare sire of A.P. Indy line stakes winners, is a three-parts-brother to the dam of Girolamo, and Not For Love is a very close relative to his dam. It will also pay to emulate the Mr. Prospector/Northern Dancer cross that produced the dam of Girolamo. There are also four grade one winners bred on the cross of A.P. Indy with mares from the line of Alydar (Raise a Native son who is a genetic relative to Mr. Prospector), and sons of Alydar who have worked under A.P. Indy include Easy Goer and Jeblar. From the Majestic Light branch of Raise a Native, Maria's Mon is sire of Kentucky Derby winner Super Saver out of a sister to Girolamo.

A.P. Indy and his sons have done well with numerous branches of the Northern Dancer line. Here, the Storm Cat branch looks particularly interesting, with Tale of the Cat, Hennessy, Tabasco Cat, Tactical Cat, and Forestry all appearing as broodmare sires of grade one winners sired by stallions bred on the A.P. Indy/Mr. Prospector cross. Other Storm Cat sources include Giant's Causeway, Storm Boot, Forest Wildcat, Stormy Atlantic, Stormin Fever, Harlan's Holiday, Bernstein, Mountain Cat, Tabasco Cat, Sir Cat, Freud and Tomorrows Cat. In addition to the Storm Cat branch, we can also note a Champion Two-Year-Old by a son of A.P. Indy out of Storm Bird son, Summer Squall (a half-brother to A.P. Indy). The cross of A.P. Indy line stallions over mares descending from Northern Dancer through Deputy Minister has also worked well, including stakes winners from mares by Awesome Again, Dehere, and Silver Deputy, with other sources including Salt Lake, Touch Gold, Deputy Commander, Forest Camp, and French Deputy. Among other branches of Northern Dancer that have enjoyed success under A.P. Indy line stallions are Nureyev (including Theatrical and Zilzal); Nijinsky II (including Royal Academy, Sky Classic, Seattle Dancer - giving inbreeding the dam of Seattle Slew - Strawberry Road, Shadeed and Alydeed); Danzig (including through Chief's Crown, Danehill, Danzig Connection, Deerhound, Langfuhr, Honor Grades - giving inbreeding to the dam of Seattle Slew - Belong to Me, Boundary, Ghazi, Lost Soldier, and Sea Hero), and Dixieland Band (particularly though Citidancer, with Dixie Union also looking interesting).

The A.P. Indy line is beginning to work well with Roberto line mares, including stakes winners out of mares by Red Ransom, Kris S. (and his sons, Arch and You and I) and Dynaformer. Roberto is a Hail to Reason line horse, and A.P. Indy line stallions also have stakes winners from the Halo and Cure the Blues branches of Hail to Reason. Successful sources of Halo include Devil's Bag (himself sire of Devil His Due, Abaginone, Twilight Agenda, and Diablo), and a brother to by Saint Ballado (sire of Captain Bodgit, Sweetsouthernsaint, Yankee Victor, Straight Man and Flame Thrower), Southern Halo (who will be particularly good through More Than Ready), Jolie's Halo and Sunny's Halo. From the Cure the Blues branch of Hail to Reason there is an A.P. Indy line stakes winner out of a mare by Take Me Out, and American Chance should also work well.

There is a grade one winner by an A.P. Indy/Mr. Prospector stallion out of a mare by Private Account, from the Damascus line. Private Account is a half-brother to the granddam of Girolamo, and can be brought in through Private Terms and his son, Afternoon Deelites, Personal Flag, Corporate Report, Secret Hello, Unaccounted For and Valley Crossing. We can also note Damascus working under A.P. Indy through Gilded Time, and Fly So Free (by Time For A Change).