9-hydroxystearic acid, an isomer of the active metabolite α-hydroxystearic acid, arrests HT29 colon cancer cells in G0/G1 phase of the cell cycle via overexpression of p21 [37], induces differentiation of HT29 cells [38] by inhibition of histone deacetylase 1 [39] and interrupts the transduction of the mitogenic signal [40]. This evidence concerns the gene HDAC1 and colonic neoplasm.