ADRB3 and neoplasm: By 18 weeks of age, whereas all PyMT-ADRB3+/+ mice developed multiple tumors, reduced incidence of tumor formation (100% vs. 70%, P = 0.003) and dramatic reduction in tumor volume were found in PyMT-ADRB3-/- mice (3403 ± 321 vs. 1,743 ± 150 mm3, P < 0.05) (Fig. 5A–C).