Having in mind the low overall activity of 5-LO in the tumor cells, we have recently established a CRISPR/Cas-mediated knock-out of 5-LO in two colon cancer and an osteosarcoma cell line and performed RNA-Seq to investigate if non-canonical activities of 5-LO might influence the overall gene expression in these cancer cells and thus cancer cell function. This evidence concerns the gene ALOX5 and osteosarcoma.