RB1 and prostate carcinoma: NCI-LYM-1 harbored biallelic loss-of-function events for PTEN, TP53, and RB1, the most frequently silenced tumor suppressors in AVPC [26, 27], with the first allele of all three genes being lost via loss-of-heterozygosity, the most common pattern of sequential haploinsufficiency in prostate cancer [28, 29].