Illumination was continuous throughout PC alone; control illumination was for the same duration under normoxic conditions (see methods & panel A). Two-way ANOVA comparing +ATR vs -ATR in each group. *p = 0.016, n = 11,11,4,4,6,6 independent experiments each bar from left to right, each averaged from 3 technical replicates with at least 15 animals per replicate. Data show mean ± SEM. 