Nested meta-analysis of studies comparing specific mucins in the gastric epithelium demonstrating increased mucin expression in Helicobacter pylori positive than in Helicobacter pylori negative patients. A: MUC2 (3 papers and 4 studies); B: MUC6 (6 papers and 11 studies); C: STn (4 papers and 5 studies); D: PcA, Tn, T, T1, LeA, SLeA, LeB, TN, AB-PAS (5 papers and 12 studies); E: MUC1 (4 papers, 4 studies).