CNR1 and colorectal carcinoma: The complexity of CRC cell lines response to quercetin is augmented if the study of Refolo et al., in which it was demonstrated that a relatively low concentration of this flavonol (50 μM) upregulated specifically the cannabinoid receptor 1 (CB1-R) expression in Caco-2 and DLD-1 cell lines at a concentration in which quercetin exerted growth inhibition by apoptosis induction.