LYN and B-cell chronic lymphocytic leukemia: On the other hand, in a mouse model of chronic lymphocytic leukemia (CLL) with endogenous PTPROt complete depletion due to disruption on the distal promoter of PTPRO gene, loss of homozygous PTPROt alleles in CLL cells leads to reduced activity of the BCR signaling, most likely owing to the lack of dephosphorylated Lyn at Y507 (54).