SMAD5 KD phenocopies miR-155 effects on TGF-β1-mediated RB phosphorylation. Western blot analysis of hypo-pRB (left panels) was performed in the DLBCL cell lines Ly7 (A), Ly18 (B), and DHL5 (C) subjected to RNAi-mediated SMAD5 suppression. Upon TGF-β1 exposure (5 ng/mL), the abundance of the hypo-pRB (active RB) isoform increases in the control RNAi cells, but not, or to a lesser degree, in their isogenic counterparts transiently (Ly18 and DHL5) or stably (Ly7) expressing 2 independent RNAi sequences directed at SMAD5 (left panels). In the right panels, western blots depict the effectiveness of the SMAD5 KD; densitometric quantification of the SMAD5 suppression is shown under each panel. β-actin imunoblotting was used to confirm proper loading. The data shown in this figure were confirmed in 2 to 4 biological replicates.