Mycoplasma hyorhinis promotes colony formation of cancer cells. A. Verification of Mycoplasma hyorhinis infection. Mycoplasma-infected (+) and non-infected (-) MGC803 and AGS cells were harvested and cell lysates were subjected to Western blot analysis with PD4 antibody against p37 protein. Purified p37 protein  was used as positive control. B. Colony formation assay. 500-1000/well cells were cultured in 6 well plates for 5-10 days. The cell colonies were fixed by acetone-methanol (1:1) and stained with Crystal Violet. The numbers of colonies were counted and the graphs were the composite results from three independent experiments. There were more colonies in infected cells than non-infected cells (P < 0.05).