MAPK1 and breast cancer: A growing number of clinical trials [24 clinical trials till 2018, Table 4 in (75)] are currently underway to evaluate the combination of PI3K and MEK inhibitors in various cancers with specific types of molecular alterations (e.g. RAS/RAF/MEK/ERK pathway activation), namely malignant melanoma with BRAF or NRAS mutations and colorectal, ovarian, pancreatic, and basal-like breast cancers, etc., with various response results (30, 76–79).