ETNK2 and gastric cancer: To facilitate analysis of ETNK2 function in GC cells, we used the MKN1 cell line for genome editing, because it was originally derived from a liver metastasis lesion from a GC patient, expressed one of the highest levels of ETNK2 mRNA, had high abilities in cell migration and invasion in our previous studies, and is engrafted in nude mice for subcutaneous and in Nod-SCID mice for hepatic metastasis xenograft models.25,30 We generated two MKN1 cell lines with stable ETNK2 KO (KO ETNK2-1 and ETNK2-2) using the CRISPR-Cas9 method.