Importantly, miRNA profiling of our series of patient-derived specimens (n = 96 MM, n = 29 plasma cell leukemia (PCL) cases) disclosed a significant inverse correlation only between miR-22 and MYC expression in both MM and PCL cases, with an r value of −0.53 in the latter, demonstrating a clear correlation with disease progression (Figure 1a and Figure S1a). Here, MYC is linked to plasma cell leukemia.