Fig. 7. Apoptosis correlates with PCNA expression in 
-irradiated whole organ cultures. Mammary glands from unprimed virgin BALB/c-Trp53+/+ mice were cultured for 96 hours in unsupplemented (untreated), hormone- or growth factor-supplemented medium. Hormone-supplemented medium contained estrogen (1 ng/ml) plus progesterone (1 µg/ml), while growth factor-supplemented medium contained EGF (20 ng/ml) plus TGF
(20 ng/ml). The percentage of cycling cells was determined immunohistochemically by calculating the percentage of PCNA-positive epithelial cells, while the percentage of apoptotic cells was determined by TUNEL assay on whole organ cultures 6 hours after treatment with 5 Gy of -radiation. Asterisks indicate values statistically different from irradiated controls in unsupplemented medium (P<0.05). Error bars represent s.e.m.
