SPHK1 and cancer: Moreover, the SphK1/SphK2 product, S1P was shown to target histone deacetylases (HDAC1/2), tumor necrosis factor receptor associated factor 2 (TRAF2), human telomerase reverse transcriptase (hTERT), and NF-κB nuclear activities linked to cancer initiation and progression [24,33,34,37,38,39].