FIG. 6.

Abrogation of radiation-induced growth arrest in the epidermis from K14E6 mice with low or high transgene copy number. Shown are percentages of BrdU-positive cells in the epidermis of K14E6 line 5737 mice carrying a high copy number of the transgene, K14E6 line 5718 mice carrying a low copy number of the transgene, and nontransgenic FVB/N mice that were treated or not treated with 5 Gy of ionizing radiation. Provided are the average values for three mice in each group ± 1 standard deviation. The 10-fold reduction in percentage of BrdU-positive cells in nontransgenic FVB/N mice is an indicator of the radiation-induced growth arrest. Note absence of reduction in the percentage of BrdU-positive cells in the epidermis from mice of both lines 5737 and 5718.