HOXA9 and leukemia: However, when comparing baseline expression levels of these genes within the MLL-r leukemia cell line group itself, it became evident that the MLL-r cell lines that are sensitive to CCI-007 have significantly lower baseline levels of MEIS1 and BCL2 mRNA and cluster separately from resistant cell lines based on expression levels of HOXA9, MEIS1 and BCL2, indicating that this compound targets a particular subpopulation of MLL-r leukemia cells.