Human CCND1 gene is located in the q13 region of chromosome 11 and encodes cyclin D1. Its main function is to regulate the transition of the cell cycle from the early stage of DNA synthesis (G1 phase) to the DNA synthesis phase (S phase). Overexpression of CCND1 gene will affect the normal cell cycle, leading to a variety of tumor diseases. CCND1 gene amplification is present in thyroid cancer, non-small cell lung cancer, breast cancer, bladder cancer and other tumors.