MCL1 and plasma cell myeloma: In addition to the insights gleaned from in vitro studies highlighting the critical threshold of Mcl-1 expression required for sustaining myeloma cell viability, clinically, the overexpression of Mcl-1 is detected in 52% of MM patients at diagnosis and 81% at relapse, implying that Mcl-1 level corresponds with disease progression and correlated with a shorter lifespan (Wuilleme-Toumi et al., 2005).