CLL primary cells from one patient sample (CLL599) was either unstimulated or stimulated with αIgM and treated with 5 μM of idelalisib for increasing time points (30 min, 2 h and 24 h) and the immunoblot technique was carried out to evaluate Mcl-1 and Bcl-2 proteins. This evidence concerns the gene MCL1 and B-cell chronic lymphocytic leukemia.