MMP9 and autoimmune polyendocrinopathy: The expression of SAMD1 decreased and the levels of anti‐B2GPI, anticardiolipin antibody, MMP‐9, iNOS, ICAM‐1, and MCP‐1 increased in human umbilical vein endothelial cells incubated with 10% peripheral blood serum of antiphospholipid syndrome (APS) patients, with enhanced cell senescence and reduced cell proliferation, viability, migration, and angiogenesis.