As one of the ligands for the TAM (Tyro3, Axl, and Mertk) receptor tyrosine kinases, PROS1 was proven to be a strong stimulator of p-Erk through ProS1-Tyro3-Erk signaling pathway in some human cancer cell lines52, which indicated PROS1 may also participate in the ERK pathway downstream of BRAFV600E. Here, MAPK1 is linked to cancer.