On the other hand, p66Shc deficiency in CLL B cells from patients with unfavorable prognosis directly correlates to their abnormally low levels of the surface receptor S1PR1 [84] whose ligand, the sphingolipid S1P (sphingosine 1-phosphate), promotes lymphocyte egress from lymphoid organs [94]. This evidence concerns the gene S1PR1 and B-cell chronic lymphocytic leukemia.