ATF4 and cancer: Importantly, Bagheri-Yarmand et al.19 reported that RET contributes to cancer cell viability via the direct repression of ATF4 at the promoters of pro-apoptotic targets NOXA and PUMA. Despite the well-documented pathogenic, diagnostic and prognostic roles of RET in MTC 20, its precise role in BTZ-induced apoptotic cell death in OS remains unknown.