SPHK1 and hepatocellular carcinoma: Similarly, miR-98 expression downregulates activin receptor-like kinase-4 (ALK4) and metalloproteinase-11 (MMP11) expression, and miR-506 downregulates Sphingosine kinase 1 (SPHK1), thereby inhibiting cell growth and angiogenesis in breast cancer and hepatoma cell models, respectively [24, 25].