However, while SKIP has been shown to inhibit SPHK function in fibroblasts [153,154], a study in K562 Chronic Myelogenous Leukemia cells reported that SKIP acts more as a positive, rather than negative, regulator of SPHK1/S1P [155]. This evidence concerns the gene MBTPS1 and chronic myelogenous leukemia, BCR-ABL1 positive.