ERK3 knockdown significantly decreased the levels of both basal and EGF-induced GTP-bound CDC42 and RAC1 in primary (HMEC) (Figure 2B, D, and F) and triple-negative breast cancer (MDA-MB231) mammary epithelial cells (Figure 2C, E, and G), respectively. Here, MAPK6 is linked to triple-negative breast carcinoma.