PROK2 and Arthritis: Daily intraperitoneal administration of the PK2 antagonist PKRA7 to CIA mice before the onset of arthritis from Day 21 resulted in significantly lower arthritis scores in treated mice compared to control CIA mice on Days 28, 31, 33, and 35 (Fig. 5a; P = 0.0104, P = 0.0018, P < 0.001 and P < 0.001, respectively).