miR-19 promotes c-Myc-induced B-lymphomas by repressing apoptosis (Mu et al., 2009; Olive et al., 2009), yet has little effects in promoting Rb-deficient retinoblastomas (Conkrite et al., 2011); miR-17 allows the bypass of Ras-induced senescence by promoting proliferation (Hong et al., 2010), yet fails to affect c-Myc-induced lymphomas, possibly due to its functional redundancy with c-Myc. This evidence concerns the gene RB1 and lymphoma.