CTBP1 and neoplasm: To study the effects of RAI2-induced CtBP polymerization in a relevant tumor cell model, we chose the VCaP PC cell line because of its high endogenous RAI2 expression and hence the presence of distinct CtBP/RAI2 foci (Fig. 4a, b, Supplementary Figs. 15, 16a, b).