As PD146176 also inhibited the production of 13-HODE in human colon cancer HCA-7 cells, we postulate that PD146176-induced decreases in 13-HODE levels in HCA-7 tumors were due to inhibition of human HCA-7 tumor cell 15-LOX-1 activity and in mouse MC38 tumors, were due to inhibition of 12/15-LOX activity (particularly in macrophages). This evidence concerns the gene OLR1 and colonic neoplasm.