Abstract: Objective To analyze the influence of bone morphogenetic proteins (BMPs) from CT26 on PD-L1 of dendritic cells and macrophages. Methods In vivo, we respectively inoculated CT26 colon cancer cells subcutaneously and intraperitoneally to BALB/c mice.The mice were randomly assigned to three groups and treated with ① normal saline; ② BMPs inhibitor LDN193189; ③ BMPs inhibitor LDN193189 combined with paclitaxel, respectively. The treatments started on the eighth day after inoculating, when the tumor volume reached 150 mm3 or the abdominal circumference was greater than 6 cm. After 2 weeks of treatments, the mice were sacrificed.The counts of dendritic cells and macrophages and the expression of PD-L1 in tumors or ascites were detected by flow cytometry (FCM).In vivo, the dendritic cells and macrophages from normal BALB/c mice bone marrow were exposed to: ① no treatment; ② CT26 supernatant; ③ CT26; ④ CT26 supernatant and LDN193189; ⑤ CT26 and LDN193189; ⑥ CT26 supernatant, LDN193189 and paclitaxel; ⑦ CT26, LDN193189 and paclitaxel. BMPs from CT26 was detected by ELISA.The counts of dendritic cells and macrophages and their PD-L1 expressions were detected by FCM. IRF-1 expression was detected by real-time (RT)-PCR and Western blot. Results In vivo, LDN193189 treated mice had the greatest tumor size or abdominal circumference, with least dendritic cells andCM(155.3mmmacrophages and expressions of PD-L1.In vivo, ELISA test results showed that the concentration of BMPs inCM）