Calpain inhibitor II (CPI-2) is a cell-permeable inhibitor of calpain I, calpan II, cathepsin L and cathepsin B.
Calpain inhibitor II 2 at 50 or 100 μM has shown to induce apoptosis in (acute lymphoblastic leukemia) ALL (ALL-1, RS4;11, and JURKAT) and (non-Hodgkin’s lymphoma) NHL (RAMOS and DAUDI) cell lines, as measured by MC540 single fluorescence. Additionally, studies have shown that neither BTK nor LYN were required for calpain inhibitor II induced apoptosis. Calpain inhibition with calpain inhibitor II has been demonstrated to induce apoptosis-promoting caspase system [1]. Unlike calpain inhibitor I, calpain inhibitor II cannot inhibit NFkB and sensitize DLD1-TRAIL/R cells to the TRAIL protein [2].
References:
[1] Zhu DM1, Uckun FM. Calpain inhibitor II induces caspase-dependent apoptosis in human acute lymphoblastic leukemia and non-Hodgkin's lymphoma cells as well as some solid tumor cells. Clin Cancer Res. 2000 Jun;6(6):2456-63.
[2] Zhu H1, Zhang L, Huang X, Davis JJ, Jacob DA, Teraishi F, Chiao P, Fang B.Overcoming acquired resistance to TRAIL by chemotherapeutic agents and calpain inhibitor I through distinct mechanisms. Mol Ther. 2004 May;9(5):666-73.