PDCD4 and colorectal carcinoma: More studies have demonstrated that programmed cell death 4 (PDCD4) is reduced during CRC tumorigenesis, along with the transformation of normal tissue to adenocarcinoma COX2/PGE2-mediated repression of PDCD4 occurring via the induction of miR-21 [79], and the reduction of PDCD4 is well-associated with a shorter survival time of CRC patients [80].