SHC1 and B-cell chronic lymphocytic leukemia: Based on their residual levels of p66Shc, CLL patients were then grouped in high p66Shc (high-p66) and low p66Shc (low-p66) expressing patients, according to an arbitrarily set threshold (0.25, corresponding to the median ddCt p66Shc mRNA of all CLL patients, Figure 1A).