PDCD4 and B-cell chronic lymphocytic leukemia: PDCD4 may be a common link between signaling and mRNA translational control since PDCD4 expression is downregulated following exposure of CLL cells to other microenvironmental signals, including the combination of bone marrow-derived stromal cells, CD40 ligand and CpG oligodeoxynucleotides (which stimulate toll-like receptor signaling), or the chemokine CXCL12 [98, 99].