We next tested FACS-purified GFP+ dim, bright, or mixed-ALL cells for B cell- (pax5, cd79b, ighz, etc.), T cell- (cd4, cd8, il7r, etc.), and lymphoblast- (rag2, igic1s1, etc.)specific transcripts, as well as the GFP and hMYC transgenes by quantitative reverse-transcriptase PCR (qRT-PCR), analyzing all GFP+ cells as one population without separating GFPlo and GFPhi peaks. The gene discussed is CD79B; the disease is acute lymphoblastic leukemia.