Consistent with this notion, we found that silencing ERK1/2 with siERK1/2 siRNA (Fig. 1c), while not acutely affecting cell viability, also impaired the capacity of Wnt5a to enhance CLL-cell proliferation relative to that of CLL cells treated with control, nonspecific siRNA (siCtrl) (Fig. 1c-e). This evidence concerns the gene MAPK3 and B-cell chronic lymphocytic leukemia.