Western blot analysis further indicated that the expression levels of chemoresistance-associated protein P-gp and anti-apoptotic protein Bcl-2 were significantly increased, and pro-apoptotic protein Bax was significantly decreased in gastric cancer cells co-cultured with MR macrophages (Fig. 4H, I; HGC27: p = 0.007, p = 0.005, p < 0.001; MKN45: p < 0.001, p < 0.001, p < 0.001). This evidence concerns the gene PGP and gastric cancer.