Programmed cell death protein 4 (PDCD4) levels are elevated during apoptosis and absent in many cancer samples.1,2 Loss of PDCD4 expression is an important event in cancer cell progression whereas the restoration of PDCD4 protein can lower metalloproteinase activity and possible metastasis.2,3 The known isoforms of PDCD4 differ only at the N-termini with isoform 1 comprised of 468 amino acids and isoform 2 comprised of 458 amino acids. Each isoform contains two MA-3 domains essential for PDCD4 binding eIF4A and thereby suppression of cell cycle regulation and growth factor production.3,2,4 This antibody is capable of detecting both PDCD4 isoforms. Additional protein modifications are possible and can explain the range of masses detected by the immunoblotting (52-64 kDa).1 The molecular mechanisms of PDCD4 influence on tumor suppression are becoming known but warrant further research.3,5,2