May play a role in growth regulation. Is associated with G2/M phase arrest in response to DNA damage. May be an intermediate by which p53 mediates its role as an inhibitor of cellular proliferation (By similarity). DNA replication foci after DNA damage. High levels in skeletal muscle, ovary, kidney and colon. Very low levels in normal cells during G1 phase, which increase as cells enter the S phase and stay high throughout the S and G2/M phases. In breast cancer cells consistent high levels are found throughout the cell cycle. Activated in breast and prostate cancer cells. Activated by actinomycin-D induced DNA damage. Belongs to the cyclin family. Cyclin G subfamily.