MCL1 and neoplasm: However, unlike the human counterpart, the Eμ-xbp-1s MM transcriptome revealed evidence of prominent activation of proapoptotic tumor suppression mechanisms characterized by downregulation of the antiapoptotic genes, MCL1 and BCL2, which are typically upregulated or amplified in aggressive human MM cases (Carrasco et al., 2006; Le Gouill et al., 2004; Mitsiades et al., 2004).