APC and malignant colon neoplasm: Moreover, Jette et al. found that diminished atRA biosynthesis activity was accompanied with decreased DHRS9 expression in a number of CRC-derived cell lines and that reintroduction of the tumor suppressor APC into APC-deficient colon cancer cells not only induced DHRS9 expression but also increased the conversion of retinol to retinoic acid [15].