COL21A1, COL22A1, COL23A1 and COL24A1 mRNA patterns in matched pairs of head and neck tumors and adjacent normal mucosal tissues. The relative expression levels of (A) COL21A1, (B) COL22A1, (C) COL23A1 and (D) COL24A1 were analyzed in the clinical samples. The changes between cancerous and normal mucosal tissues were considered to be significant, as determined by the Student’s t-test and the Wilcoxon signed-rank test. The P-values were calculated by the Wilcoxon signed-rank test. T, tumor; N, normal mucosal tissues.