MCL1 and neoplasm: Indeed, knock-down of MCL1 can restrict tumor initiation in vivo when tested in limiting dilution transplantation assays with the SUM159PT TNBC cell line, whilst MCL-1 overexpression increases the stemness of MDA-MB-468 cells (TNBC) as determined by an increased CD44hi/CD24lo cell-surface profile and enhanced tumorsphere-forming capacity [49].