Fig. 4

Site-specific methylation frequencies for nine prostanoid receptor genes. a Comparison of methylation statuses of the promoters of the nine prostanoid receptor genes in patients with hypopharyngeal, laryngeal, oropharyngeal, or oral cancer. Filled boxes indicate the presence of methylation, and open boxes indicate the absence of methylation. b The mean MI values for various groups were compared using Student’s t-tests. *P < 0.05