Idelalisib not only thwarts the PI3K/Akt/mTOR pathway but also inhibits cell migration towards chemokines and adhesion to stromal cells, which, just like with ibrutinib, leads to an initial increase in the number of lymphocytes in the peripheral blood caused by lymphocyte migration out of the tissues in CLL. The gene discussed is PIK3CD; the disease is B-cell chronic lymphocytic leukemia.