Claudin-18 knockdown by siRNA. (A) Claudin-18 siRNA significantly decreases the mRNA level of claudin-18 in MKN74.

<p>(B) Staining of claudin-18 is reduced by claudin-18 siRNA treatment. Bar = 50 µm. Each value represents the mean ± SD of 3 independent experiments. **<i>P</i><0.01 vs. control or control siRNA.</p

HE staining and immunofluorescence staining of claudin-18 in gastric cancer (GC) lesions and surrounding gastric mucosa.

<p>(A) HE staining of gastric mucosa with non-intestinal metaplasia (non-IM), intestinal metaplasia (IM), and cancer. Claudin-18 is detected in gastric mucosa with non-IM at the surface border and lateral membrane of the epithelial cells, but not with IM or cancer. White bar = 100 µm, Yellow bar = 50 µm. (B) Claudin-18 level is significantly lower in GC than in non-IM or IM. The level is also significantly lower in IM than in non-IM. ^#<i>P</i><0.05 vs. IM. **<i>P</i><0.01 vs. non-IM.</p

Clinicopathological features of gastric cancer patients.

<p>T1a; tumor confined to the mucosa, T1b; tumor confined to the submucosa,</p><p>U; upper third, M; middle third, L; lower third <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074757#pone.0074757-JapaneseGastricCancerAssocciation1" target="_blank">[18]</a></p

Effect of claudin-18 knockdown on the proliferation and invasion of GC cells.

<p>(A) Claudin-18 siRNA treatment significantly induces cell proliferation. (B) Claudin-18 siRNA-transfected MKN74 cells show a significantly higher invasion ratio compared to control or control siRNA-transfected cells. Typical images are presented at the top. Bar = 500 µm. Each value represents the mean ± SD of 3 independent experiments. **<i>P</i><0.01 vs. control or control siRNA.</p