FOLH1 and Familial prostate cancer: FM‐DEL1 and FM‐DEL2 were screened for activity against recombinant human ACP3 (hACP3 or PAP), a prostate cancer‐associated antigen alternative to PSMA.[26, 27, 28] To identify potential hits with cross‐species reactivity, FM‐DELs were also tested against murine recombinant ACP3 (mACP3), which facilitates future translational activities.