Thus , post-EPA , PGE2 : PGE3 was lower in unchallenged ( 12:1 versus 28:1 ; p < 0.05 ) and UVR exposed ( 12:1 versus 54:1 ; p < 0.01 ) skin ; 12-hydroxyeicosatetraenoic acids :12 - HEPE was lower in UVR-exposed skin ( 3:1 versus 11:1 ; p < 0.001 ) .