NOTCH1 and B-cell chronic lymphocytic leukemia: Since mutation of c7541_7542delCT, resulting in a frameshift deletion of NOTCH1, represents more than 80% of NOTCH1 mutations in CLL, and has been shown to affect CD20 expression in CLL [13], the NOTCH1 genomic region between 7270–7680 bp in I83-E95 cells was sequenced.