The low serum GKN1 expression was specific to GC, as patients with other types of tumors, such as HCC (6.26 ± 0.95 ng mL−1) or CRC (6.07 ± 0.92 ng mL−1), had serum GKN1 levels similar to those of HDs.[57] These findings suggest that low exosomal GKN1 expression could be a potential indicator of GC. Here, GKN1 is linked to hepatocellular carcinoma.