SMPD1 and Miyoshi myopathy: Next, we determined the presence of neutral and acid sphingomyelinase mRNA as well as total secreted and cellular SMase in human multiple myeloma cell lines (HMCL) representing different genetic subtypes of MM, including JJN3 (c-Maf), LP1 (MMSET/FGFR3), OPM2 (MMSET/FGFR3), and U266 (CCND1).