Protein expression of COX-2 in the erythrocytes of chickens at time intervals of 0, 2, 6 and 10 h (protein bands derived from Western blot). Data represent mean ± SEM. Asterisks (*) indicating significant differences compared to control groups (*P < 0.05; **P < 0.01; ***P < 0.0004; ****P < 0.0001; ns, not significant); C, control; Exp, experimental.