FOS and endometrium adenocarcinoma: Furthermore, we confirmed that RCAN1-4 is a potent negative regulator of CXCL8 in vitro and ex vivo in endometrial adenocarcinomas explants and that the regulation of transcriptional activation of CXCL8 by PGF2α occurs via the co-operativity between AP1 and NFAT DNA binding elements.