REDD-2 (regulated in development and DNA damage response 2), also designated Rtp801L or DDIT4L (DNA-damage-inducible transcript 4-like), is a 193 amino acid cytoplasmic protein belonging to the DDIT4 family and is predominantly expressed in skeletal muscle. Considered a stress-inducted protein, REDD-2 is a negative regulator of the mTOR (mammalian target of rapamycin) pathway. mTOR is a serine/threonine kinase that plays an essential role in cell growth control and is an important regulator of skeletal muscle size. Highly expressed in human atherosclerotic lesions and macrophages, REDD-2 mediates monocyte cell death through reduction of Trx (thioredoxin-1) expression. REDD2 expression in macrophages increases oxidized LDL (oxLDL)-induced cell death, suggesting that REDD2 may play a critical role in arterial pathology.