has_role vitamin A metacyc.compound:Vitamin-A vitamin-A wikipedia.en:Vitamin_A vitamin A vitamers vitamins A vitamin A vitamer SNOMEDCT:82622003 MESH:D014801 Any member of a group of fat-soluble retinoids produced via metabolism of provitamin A carotenoids that exhibit biological activity against vitamin A deficiency. Vitamin A is involved in immune function, vision, reproduction, and cellular communication. chebi_ontology CHEBI:12777 isoprenoid vitamin (role)