MAPK1 and breast cancer: Both ERK and AKT are known to be involved in the regulation of ULBP2 expression.24, 25, 26 In addition, members of the miR-17-92 cluster target and inhibit the MAPK/ERK signaling pathway,27, 28 and miR-20a directly targets MAPK1 (ERK2) and inhibits its expression in BC cells (Wengong Si et al. unpublished data).