MAPK3 and thymoma: To confirm this point, we used established AB thymoma cell line Thy0517 and the results showed that KITLG suppression could downregulate the expression of GRB2, p‐BRAF, p‐MEK1/2, and p‐ERK1/2, whereas KITLG overexpression had a profound activating effect on the MAPK pathway in Thy0517.