A final and significant outcome of our study is the identification of a restricted number of genes which are up-regulated (IRF1, CTSS, PSMB10, CYP26B1, DHRS3 and TINAGL1) and down-regulated (AHNAK2) by ATRA in all the retinoid-sensitive gastric-cancer cell-lines considered. This evidence concerns the gene CYP26B1 and gastric cancer.