Hypoxia-Inducible Factor 1 (HIF-1) is a protein that plays a crucial role in how cells respond to low oxygen levels, a condition known as hypoxia. It helps regulate the expression of various genes that enable cells to adapt to reduced oxygen availability, promoting processes like angiogenesis (the formation of new blood vessels) and metabolism adjustments. HIF-1 is composed of two subunits: HIF-1α and HIF-1β. Under normal oxygen conditions, HIF-1α is rapidly degraded, but during hypoxia, it stabilizes and accumulates in the cell. This stabilization allows HIF-1 to activate genes that help cells survive and function effectively in low-oxygen environments.