ERBB2 and breast cancer: Chia et al. also reported that AR-stimulation required HER2 expression in order to lead to its non-genomic effects, while ERK1/2 was also found to regulate AR expression via the activity of cAMP response element binding protein 1 (CREB1), thus forming a complete positive feedback loop that connects AR-MAPK-ELK1 in ER-negative/HER2-positive BC [84].