TBC1 domain family member 4 (TBC1D4), also designated AS160, can be insulin- and/or AKT1-induced. Insulin-stimulated phosphorylation is required for GLUT4 translocation. TBC1D4 may play a role as a GTPase activating protein for proteins in the Rab family. It is expressed primarily in skeletal muscle and heart, as well as spleen, lymph node and leukocytes. Defects in the TBC1D4 gene may cause atopic dermatitis (AD), sometimes referred to as eczema, an atopic chronic skin disease. The skin of affected individuals reacts to irritants or allergens and becomes red, flaky and itchy. The skin is also more vulnerable to inflammations, and symptoms can grow or disappear over time.