SMPD2 and neoplasm: Additionally, activation of HepG2 and Huh-7 tumor cells with ARA led to considerable decrease in surface membrane SM content as assessed using the lysenin test, increase in nSMase activity as judged by the Sphingomyelinase Amplex Red Assay, likely mediating highly significant (P < 0.0001) reduction in HepG2 and Huh-7 tumor cells proliferation level in the Alamar blue test (Fig. 6) [64].