show Abstracthide AbstractMAF from pika Epas1-3FLAG knock-in mice were extracted and immortalized. After 12h DMOG treatment, cells were conducted for the ChIP-seq (Bmal1,Flag). We found that in knock-in mice fibroblasts, EPAS1-3FLAG can bind to similar E-box locus compared with BMAL1. Fibroblasts from mouse, rat, rabbit and Tibetan pika were extracted (and Tibetan pika fibroblasts were immortalized). RNA was extracted at 90% confluency. We found that Per2 mRNA level was significantly lower in Tibetan pika fibroblasts compared with other species. Overall design: To evaluate the binding site of Epas1 and the mRNA level of core clock genes in different species