HMOX1 and squamous cell carcinoma: Numerous studies have confirmed that PCs are good for controlling various disorders, such as autoimmune arthritis, diabetes, cardiovascular disease and squamous cell carcinoma, through fighting OS damage via inhibition of mitogen-activated protein kinase/nuclear factor kappa-B (MAPK/NF-κB) pathway and activation of heme oxygenase-1 (HO-1) signal [20–24].