ATF4 and non-small cell lung carcinoma: However, Sun et al. activated the PERK-ATF4-CHOP signaling pathway through TIIA, and then increased the expression of ULBP1 and DR5 through ATF4 and CHOP, leading to enhanced NK cell-mediated killing of NSCLC cells, which seemed to indicate a connection between ULBP1 and CHOP(Sun et al., 2021).