✓mediates all-trans-retinoic acid (ATRA) effects on an increase in ceramide, G0/G1 cell-cycle arrest, and suppression of p-RPS6 via inhibiting p-S6K in a breast cancer cell line MCF7 [184]✓Overexpression of nSMase2 induces G0/G1 growth arrest in MCF7 cells [184]. This evidence concerns the gene RPS6 and breast cancer.