Using microarray expression data, we found that the mRNA-encoding DEPTOR, an inhibitor of mTORC1 and mTORC2 kinases activities [13], was overexpressed in normal PCs (NPCs) and myeloma cells compared with normal B lymphocytes (NBLs) [14], which raised the possibility that this protein contributes to PC differentiation. Here, DEPTOR is linked to plasma cell myeloma.