GADD 153, a growth arrest and DNA damage-inducible gene, encodes a C/EBP-related nuclear protein. This protein has also been designated C/EBP-homologous protein (CHOP-10 or C/EBP zeta). GADD 153 expression is induced by a variety of cellular stresses, inducing nutrient deprivation and metabolic perturbations. GADD 153 functions to block cells in G1 to S phase during cell cycle progression and acts by dimerizing with other C/EBP proteins to direct GADD 153 dimers away from “classical” C/EBP binding sites, recognizing instead unique “nonclassical” sites. Thus, GADD 153 acts as a negative modulator of C/EBP-like proteins in certain terminally differentiated cells. GADD 153 belongs to the CBF/MAK21 family, which also includes NOC2L, NOC3L and NOC4L. NOC3L, also designated factor for adipocyte differentiation 24 or Fad24, promotes adipogenesis by controlling DNA replication during the early stages of mitotic clonal expansion (MCE).