CTSB and plasma cell myeloma: In summary, HDACi- and doxorubicin-potentiated apoptosis of myeloma cell lines was partly resulted in from activation of cathepsin B. Combination potentiated apoptosis and cathepsin B activity correlated with nuclear translocation of AIF, a mitochondrial sequestered proapoptotic factor involved in caspase-independent cleavage of DNA (Bidere et al, 2003).