3263728 PGRA progesterone receptor A 5 3263734 PGRA peripheral grating resolution acuity 3 3263730 PGRA progesterone receptor isoforms A 2 3263733 PGRA Percent Growth Rate Average 1 3263735 PGRA polyethylene glycol-retinoic acid 1 3263731 PGRA prompt gamma radiation analysis 1 3263732 PGRA psoralen gel retarding assay 1