EIF4EBP1 and B-cell chronic lymphocytic leukemia: However, in both HG-3 and OSU-CLL cells, SpiD3 modified the expression of key regulators of protein translation initiation, namely tumor suppressor programmed cell death 4 (PDCD4) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), known protein inhibitors of eIF4A1 and eIF4E, respectively (32).