AXL and autoimmune disease: The broad spectrum autoimmune disease that develops in Axl-/-Mertk-/- mice (2, 34, 50) is thought to result primarily from the presentation of autoantigens (e.g., ribonucleoproteins) that are derived from uncleared ACs that progress to necrosis, coupled with the highly inflammatory environment that characterizes double mutant immune tissues (5, 7, 51, 52).