SMPD3 and cancer: The nSMase2 is a key enzyme to convert sphingomyelin to ceramide By blocking nSMase2 using the inhibitor GW4869, knocking down nSMase2 expression or treatment with C6-ceramide, the nSMase2-ceramide pathway has been demonstrated to control ILV/exosome sorting of multiple cargos, such as proteolipid protein (PLP) in oligodendroglia cells, the prion protein in neuronal cells, and several RNAs in cancer cells [35–37].