In other studies, phytol was found to have a synergistic effect with some used chemotherapeutic drugs like β-caryophyllene, in addition to inducing apoptosis in epidermoid carcinoma cells (A431) and immortalized keratinocytes (HaCaT cells) by ROS induction, activation of the apoptotic pathway involving the release of cytochrome-c, the activation of the caspase pathway, cleavage of PARP, and an increase in the Bax/Bcl-2 ratio [45,46]. This evidence concerns the gene PARP1 and squamous cell carcinoma.