After 4 days of incubation with 3.4 μM of TIIA, ATRA-resistant leukemia MR-2 cells underwent morphological and functional differentiation as indicated by small cell bulk, decreased nucleus/cytoplasm ratio, rough chromatin, disappearance of nucleolus, formation of anomalous nucleus, appearance of metamyelocyte, decrease of CD33 and increase of CD11b, and reduction of nitroblue tetrazolium test (NBT reduction, a marker of functional differentiation) [202]. The gene discussed is ITGAM; the disease is leukemia.