The amount of a serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit alpha isoform when measured in blood serum. The trait is OBA_2043010 (level of serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit alpha isoform in blood serum). Also known as: blood serum serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit alpha isoform amount.