APC and autoimmune polyendocrinopathy: Other APS antigen targets may include non-standard APS components such as IgA aCL and anti-β2GPI antibodies, antibodies against phospholipid or phospholipid/protein antigens such as anti-phosphatidylserine/prothrombin (aPS/PT), PS, activated protein C (APC), and Annexin II/V resistance (24).