SPHK2 and breast angiosarcoma: H19 plays a key role in cholestatic liver injury and cholangiocyte proliferation in BA patients by regulating the sphingosine 1-phosphate receptor 2 (S1PR2)/sphingosine kinase 2 (SphK2) and let-7/high-mobility group AT-hook 2 (HMGA2) axis [71].