We next analyzed NOTCH3 and FCER2 (CD23) expression in CLL cells (n = 4) in relation to spontaneous as well as gliotoxin induced apoptosis on the mRNA and protein level by RT-PCR and FACS (Figure 4; see Supplemental Figure S1 for a detailed FACS analysis of CLL24 cells). This evidence concerns the gene NOTCH3 and B-cell chronic lymphocytic leukemia.