To simultaneously account for point mutations, missense and frameshift mutations affecting exon 34 and for less common 3′-UTR NOTCH1 mutations, we expressed the coding sequence of NOTCH1-ICD, but lacking the PEST domain, followed by IRES-GFP from the 5′-LTR-promoter (hereafter named NOTCH1ΔPEST) in primary CLL cells. This evidence concerns the gene NOTCH1 and B-cell chronic lymphocytic leukemia.