However, the simultaneous expression of CD38 on healthy PCs and other hematopoietic (T lymphocytes) and non-hematopoietic cells, such as epithelial, endothelial and vascular smooth muscle cells, as well as hepatocytes, goblet and columnar cells of gastrointestinal tract (205) may pose a serious obstacle to its use as a targeted MM antigen, as it may likely cause severe off tumor side effects in the already susceptible MM patients. The gene discussed is CD38; the disease is neoplasm.