IL6 and plasma cell myeloma: In multiple myeloma (MM), induction of SGK1 expression by the cytokines interleukin (IL)-6, tumor necrosis factor-α (TNF-α), and IL-21 significantly supported the growth of myeloma cells, whereas downregulation of SGK1 with shRNAs resulted in decreased proliferation of myeloma cells and reduced cell numbers (39).