We first confirmed the expression of HOXD9 protein in GC cell lines and showed that the expression levels in AGS, NCI-N87, SNU-719, MKN-45, HGC-27, BGC-823, MGC-803, and SGC-7901 cell lines were significantly higher than those in the GES-1 cell line, whereas MKN-74, SNU-1, and SNU-5 showed significantly lower expression (Fig. 1A). Here, HOXD9 is linked to gastric cancer.