SPHK2 and cancer: Although SPK2 inhibits proliferation and enhances apoptosis through its BH3 domain in different cell types,23 recent reports also show that SPK2 plays a role in regulating cancer cell proliferation and migration54, 55 and SPK2 inhibitors may serve as the therapy for cancers.56 The discrepancy may be partly due to the expression level57 and cellular distribution of SPK2 in cells.