In particular, by checking the Human Protein Atlas database (www.proteinatlas.org; 21 January 2018) three different antibodies are on the market and detect, on the same series of GC specimens, CLDN18 high expression in 36.4 to 70.0% of the cases, further supporting the need for a standardisation of testing. The gene discussed is CLDN18; the disease is gastric cancer.