STAT3 and plasma cell myeloma: Specifically, IL-6—mediated STAT3 activation has been shown to promote the survival of myeloma cells via up-regulating the expression of several survival genes [59]; intriguingly, activation of STAT3 is observed in bone marrow stromal cells present in multiple myeloma, which produce IL-6 to sustain STAT3 activation in myeloma cells [60].