CRKL and cancer: To determine whether c-Abl/Arg inhibition prevents resistance to doxorubicin, we treated cancer cells expressing highly activated forms of c-Abl/Arg (assessed by in vitro kinase assay and phosphorylation of substrates, Crk/CrkL) [31], [33], with the c-Abl/Arg inhibitors, imatinib or nilotinib, alone or in combination with doxorubicin, and measured cell viability using the CellTiter-Glo assay, which quantitates ATP, a measure of metabolically active cells [42], [43].