CLOCK and lip and oral cavity carcinoma: We have recently shown that circadian clock is a major determinant of craniofacial tissues cell homeostasis, regulating proliferation and differentiation of salivary glands (Zheng et al., 2012), dental cells (Athanassiou-Papaefthymiou et al., 2011; Zheng et al., 2011, 2013) and oral epithelium (Zheng et al., 2011; Papagerakis et al., 2014); linking circadian clock disruption with major oral, head and neck pathologies, such as oral cancer and Sjögren syndrome (Mitsiadis et al., 2014; Papagerakis et al., 2014; Matsumoto et al., 2016; Zagni et al., 2017).