Although is not clear why ovarian cancer cell lines are resistant to ATRA treatment, our study suggests that resistance to ATRA treatment is not dependent on RARA, ANXA2 or S100A10 expression as all of the serous ovarian cancer cell lines expressed similar mRNA levels of these genes (Additional file 3: Figure S1a). This evidence concerns the gene ANXA2 and ovarian serous adenocarcinoma.