TAPBP and monoclonal gammopathy: Leone et al. (20) compared the expression levels of calnexin, calreticulin, tapasin, and ERp57 genes in premalignant plasma cells obtained from patients with monoclonal gammopathy of undetermined significance, those with MM, and normal plasma cells from healthy donors and showed that these levels are higher in patients with monoclonal gammopathy of undetermined significance and MM.