BHLHE41 and breast cancer: Many of the TFs we identified, including PITX1, RARA, FOXA1, and BHLHE41/E40 (including overlapping MYC/MAX sites), are known to interact with ERα, and many belong to the previously described MegaTrans complex [22], which has been shown to play an important role in aberrant ERα-regulated gene expression in breast cancer [23].