ATF4 and neoplasm: The activation of the EIF2 signaling pathway, shown by the increased levels of key components of the EIF2 signaling pathway, p-PERK, p-EIF2A, and ATF4, significantly correlated with the knockdown of PUM1, the expression levels of which were higher in PDAC tissues than in adjacent tissues and were significantly associated with Tumor Node Metastasis (TNM) stage and overall survival time of PDAC patients81.