POLK and prostate cancer: About 22% of pancreatic, 8% of prostate, 7% of esophagus tumors lack POLI, and up to 14% of prostate-cancers lack POLK. Homozygous inactivating deletions in REV1 are very infrequent, which likely relates to the critical non-catalytic activity of REV1 to recruit other TLS-polymerase members of the Y-family [19] (Figure 1A–1D).