We initially undertook the AP-MS analysis using cells in which ectopic BRN2 was not induced by doxycycline since this basal level of ectopic BRN2-Flag was around fourfold to fivefold higher than endogenous BRN2 expressed in 501mel cells (Supplemental Fig. S1C), a similar level to that expressed in Lu1205 (Bonvin et al. 2012) or A375M (Goodall et al. 2004a) melanoma cell lines. Here, POU3F2 is linked to melanoma.