MCL1 and lymphoma: In addition, loss of Bim, combined absence of Bax and Bak or overexpression of Bcl-xL and Bcl-w have been shown to make lymphoma cells resistant to ABT-737 in vitro and in vivo, even in the absence of endogenous Mcl-1 [68], thus indicating that targeting of more than one antiapoptotic protein may be required for the full engagement of the apoptotic machinery.