A study from the Lerner laboratory showed that stimulation of the cAMP signaling pathway with PDE4 inhibitors upregulated GR transcript levels in B-CLL cells but not T-CLL cells, Sezary cells or normal circulating T or B cells, monocytes, or neutrophils (Meyers et al., 2007). Here, PDE4A is linked to B-cell chronic lymphocytic leukemia.