RB1 and retinoblastoma: Another class of mutants with enhanced RNAi is represented by lin-35/Rb, which encodes the worm homolog of the Retinoblastoma tumor suppressor, and includes other genes in the lin-35/Rb pathway such as lin-15, dpl-1 (mammalian DP), and hpl-2 (mammalian HP1) [21], [22], [23].