SDC1 and smoldering plasma cell myeloma: Recently we conducted a study to assess differential CpG methylation at about 1,500 genic loci during MM progression by profiling CD138(+) normal plasma cells (NPC) and comparing them to CD138(+) plasma cells from monoclonal gammapothy of undetermined significance (MGUS), smoldering myeloma (SMM), and MM specimens [13].