Annexin A1 / Annexin I also known as lipocortin I is a protein that in humans is encoded by the ANXA1 gene. Annexin I belongs to the annexin family of Ca2+-dependent phospholipid-binding proteins that have a molecular weight of approximately 35,000 to 40,000 and are preferentially located on the cytosolic face of the plasma membrane. Annexin I protein has an apparent relative molecular mass of 40 kDa, with phospholipase A2 inhibitory activity. Annexin I has been of interest for use as a potential anticancer drug. It inhibits the NF-κB signal transduction pathway, which is exploited by cancerous cells to proliferate and avoid apoptosis. ANXA1 inhibits the activation of NF-κB by binding to the p65 subunit.