To perform proof-of-principle in vitro study, we have done the immunofluorescence assay to examine the expression of CD44 in gastric cancer cells which HOXA11 was overexpressed or knocked down, the results have shown that CD44 is upregulated in gastric cancer cells which HOXA11 was induced, by contrast, CD44 is downregulated in MGC-803 cells which HOXA11 was knocked down (Figure 3C). This evidence concerns the gene CD44 and gastric cancer.