Antitumor activity of blank POEG-b-POM, blank POEG-b-PPPMP micelles, Doxil, DOX loaded POEG-b-POM and DOX loaded POEG-b-PPPMP micelles in a syngeneic murine breast cancer model (4T1.2). Three injections were given on day 1, 4 and 7. (B) Weights of tumors collected from different groups at the end of experiment. (C) Changes of body weight in mice receiving different treatments. (D) Photographs of tumors collected from different treatment groups at the end of experiment. Values reported are the means ± SEM, n = 5. P values were generated by one-way ANOVA using the Tukey test for multiple comparisons. *P < 0.05, **P <0.01, ***P < 0.001 (vs control).