Table 1

p21WAF1 deficiency does not increase labeling index of untreated or TPA-treated adult epidermis

Labeling index (number of BrdUrd positive cells/100 basal cells)
p21WAF1 genotype
+/++/−−/−
Age of micea
 10–12 weeks3.7 (2)c2.3 (2)2.7 (3)
 19–22 weeks3.0 (1)5.3 (1)4.5 (1)
 25–29 weeks2.9 (2)2.0 (2)3.0 (2)
Treatmentb
 TPA once22.2 (2)13.1d (2)17.7d (2)
 TPA 3 times26.9 (2)25.7 (3)18.8d (3)
  • a Control mice were analyzed at each of three ages, and 750–2300 nuclei were counted for each group.

  • b Mice were treated with TPA, as noted, and 750–3400 nuclei were counted for each genotype and treatment.

  • c Number in parentheses indicates number mice/genotype analyzed.

  • d Significantly different from p21WAF1 (+/+) (two-tailed P < 0.0001 by χ2 test). There was no statistically significant difference in labeling index of untreated skins of p21WAF1-deficient mice compared with p21WAF1 (+/+), summed across all age groups, by Mantel-Haenszel extension of χ2 test.