KCL22-r/Luciferase cells are derived from human lymphoblast-like cell line KCL22-r by stably integration of a constitutive Firefly luciferase stably expression construct. KCL22-r cells are a variant of the KCL22 cell line that is specifically used to study resistance to imatinib, a tyrosine kinase inhibitor commonly used to treat chronic myeloid leukemia (CML). Imatinib targets the BCR-ABL fusion protein, which is a key driver of CML. The paired KCL22-s and KCL22-r clones are useful cell line models of sensitivity and resistance to imatinib.  KCL22-r/Luciferase cells stably express Firefly luciferase, can be used for in vitro assays and in vivo imaging.