CDKN1A and breast neoplasm: However, Trastuzumab did not further increase PKR T446 phosphorylation, eIF2α-P, P21CIP1, and JNK/1/2 phosphorylation in BT474R cells suggesting that the sensitivity of HER2+ breast tumor cells to Trastuzumab is characterized by the induction of the anti-tumor PKR/eIF2α-P arm (Supplementary Fig. 5b).