ATF4 and triple-negative breast carcinoma: In a previous publication, the RIPK1 inhibitor necrostatin-1 abolished induction of ATF4 expression in response to cystine starvation in triple-negative breast cancer cells [40], raising the possibility that necrostatin-1 rescued BSO-treated F12-cultured cells (see Fig. 2E) by blocking ATF4 expression, and not by inhibiting necroptosis.