Signaling inhibitors: how to reprogram antigen response. Inhibition of both ERK1/2 and NF-ATc1 by treatment with U0126 and VIVIT, respectively, reverse the anergic phenotype and restore the ability of CLL cells to respond to anti-IgM stimulation in vitro. CLL cells were treated with U0126 (1 hour; A) or with VIVIT (4 hours; B), washed, and left untreated or stimulated for an additional 5 minutes with anti-IgM antibodies. The phosphorylation status of ERK1/2 was analyzed by western blotting, and band intensity was quantified by densitometry. pERK1/2 values are normalized to the control-untreated sample. (C) CLL cells were treated with U0126 (6 hours) or with VIVIT (2 hours), washed, and stimulated for additional 20 minutes with anti-IgM antibodies. NF-ATc1 activation was measured by specific ELISA assay. NF-ATc1 values are normalized to the untreated control.