SGPP1 and plasma cell myeloma: By analyzing the gene expression arrays from the publicly available myeloma GSE6477 microarray dataset, we found progressive and significant repression of SGPP1 expression with different stages of the disease compared to normal plasma cells, and the most profound inhibition of SGPP1 expression was found in relapsed MM patients suggesting that changes in sphingolipid metabolism occur during, and may contribute to, disease progression, and therefore may be clinically significant in MM.