Phospho-Cyclin D3 (Thr283) Antibody detects endogenous levels of Cyclin D3 only when phosphorylated at Threonine 283. CCND3 Regulatory component of the cyclin D3-CDK4 (DC) complex that phosphorylates and inhibits members of the retinoblastoma (RB) protein family including RB1 and regulates the cell-cycle during G (1)/S transition.