The function of HP1BP3 (heterochromatin protein 1 binding protein 3, ENSG00000127483) is as follows. Component of heterochromatin that maintains heterochromatin integrity during G1/S progression and regulates the duration of G1 phase to critically influence cell proliferative capacity (PubMed:24830416). Mediates chromatin condensation during hypoxia, leading to increased tumor cell viability, radio-resistance, chemo- resistance and self-renewal (PubMed:25100860). .