SPHK1 and neoplasm: Current evidence suggests that tumor cells overexpress sphingosine kinase 1 (SPHK1), a pro-tumorigenic enzyme responsible for synthesizing sphingosine-1-phosphate (S1P), a key signaling molecule in the TME implicated in proliferation, angiogenesis, metastasis, chemoresistance, metabolic reprogramming, and immune escape [55, 56].