FNDC5 and cancer: Although the above studies have demonstrated that changes in ATF3 and irisin levels occur in human cancer tissues, such as breast cancer (Wolford et al., 2013), lung cancer (Li et al., 2017), skin cancer (Hao et al., 2013), and CRC (Wu et al., 2014; Yan et al., 2017) tissues, little is known about circulating and adipose tissue expression levels of ATF3 and irisin in CRC patients.