Mediator complex subunit 4(MED4) is also known as mediator of RNA polymerase II transcription subunit 4 or vitamin D3 receptor-interacting protein complex 36 kDa component (DRIP36). This protein is a component of the vitamin D receptor-interacting protein (DRIP) complex which functions as a nuclear receptor coactivator. The DRIP complex is capable of activating nuclear receptors in a ligand-dependent manner.