Growth Arrest and DNA Damage-Inducible Protein GADD45 β (GADD45B) is a member of the GADD45 family. GADD45B has been shown to interact with MAP3K4, ASK1, MAP2K7, and GADD45GIP1. GADD45B is involved in the regulation of growth and apoptosis. GADD45B reacts to environmental stresses by mediating activation of stress-responsive MTK1/MEKK4 kinase, which is an upstream activator of both p38 and JNK MAPKs. In addition, GADD45B participates in the down-regulation of hepatocellular carcinoma (HCC). It may serve as a possible therapeutic target.