SMPD3 and breast neoplasm: Somewhat controversially, although the nSMase2-ceramide pathway is required for caveolin-1-mediated exosomes generation in mouse embryonic fibroblasts and MDA-MB468 breast tumor cells [44], inhibition or depletion of nSMase2 does not affect exosomal secretion of caveolin-1 in PC-3 cells [46].