Fig. 1

In absence of AREG, growth of lesions accelerated. a–d Representative images of carmine-stained AREG^+/+ PyMT and AREG^−/− PyMT mammary fat pads at 6 weeks and 12 weeks. Lesions marked by arrows. Scale bar shows 2000 μm. e Total lesion area measured for AREG^+/+ PyMT (black bars) and AREG^−/− PyMT (gray bars) mice, respectively. At least seven animals measured for 6-week group and at least three animals for 12-week group. f, g AREG^−/− PyMT palpable lesions reached 1-cm diameter more rapidly. f Kaplan–Meier plot of percentage of mice with palpable lesions less than 1 cm for AREG^−/− PyMT mice (dotted line, N = 33) and AREG^+/+ PyMT mice (solid line, N = 50). g Mean and SEM of data in (f). Statistical analysis performed using a log-rank test (f) and t test (e, g). *p < 0.05, **p < 0.01. AREG amphiregulin, PYMT polyoma middle-T antigen