The role of MYC in pathogenesis of multiple myeloma. MM pathogenesis is depicted as a linear pathway that appears to be initiated in a germinal center B cell, with subsequent transformation to a premalignant MGUS tumor that is stable but can sporadically progress to early MM, and then late MM, from which MM cell lines sometimes can be generated. The approximate fraction of cells actively cycling is depicted by length of arrow surrounding the cells. The dark nuclei reflect the antigen selection of cells after somatic hypermutation and IgH switch recombination. Some key pathogenic events are indicated, with further information in the text and references. Professional illustration by Marie Dauenheimer.