We started by assessing multiple myeloma cell lines, which have been reported to rely on MCL-1 for survival.25, 26 Using BH3 profiling, a peptide-based method that has been used extensively to determine BCL-2 family dependencies,50 we found that the H929 cell line exhibited a clear, MCL-1-dependent profile. Here, MCL1 is linked to AL amyloidosis.