CLDN18 and gastric cancer: CLDN 18.2 expression in GC was assessed by IHC staining using 43-14A antibody and the VENTANA CLDN18 (43-14A) RxDx assay (Roche Diagnostic Solutions; Tucson, AZ, USA), which recognizes the intracellular domain shared by CLDN 18.1 and CLDN 18.2 [51].