MAPK1 and Thrombocytopenia: In addition, a phase II study of Navitoclax (ABT-263) pretreated for recurrent epithelial ovarian cancers showed that thrombocytopenia was the major side effect of ABT-263 in recurrent epithelial ovarian cancer, but the poor monotherapy activity of ABT-263 was not related to the expression of p-ERK [58].