The cell commits to dividing during the G2/M phase transition, and the timing of mitotic entry is tightly regulated to guarantee correct chromosome segregation. D53, also referred to as tumor protein D52-like 1 (TPD52L1), is a coiled-coil motif-bearing member of the D52 tumor protein family. D53 intereacts with 14-3-3, a negative regulator of the G2/M transition, in breast cancer cells. Expression of D53 is highly upregulated at the G2/M phase transition in breast cancer cell lines, and deregulated expression of this protein can adversely affect the completion of mitosis. D53 may function as a signaling intermediate and/or regulator of vesicle trafficking and cell proliferation.