SPHK1 and neoplasm: As a whole, mean SphK1 activity was 432 pmol/min/mg (95% CI: 77.4–835) in tumor samples versus 6.3 (95% CI: 0.45–12.1) in noncancerous tissue, accounting for a statistically significant (p = 0.023) increase in osteosarcoma tissue compared to normal bone, suggesting that S1P is abundantly generated in osteosarcoma tissues (Figure 2).