Of previous FAM3B‐related studies, we found only one paper reporting that FAM3B inhibits the cell cycle progression of gastric cancer cells by up‐regulation of p21.42 To provide a better understanding of the molecular functions of FAM3B, we used flow cytometry to analyze the changes in the cell cycle in ECA109/TE‐1 cells transfected with the FAM3B siRNA sequence. The gene discussed is FAM3B; the disease is gastric cancer.