Table 1

Migration of S-phase cells out of the basal cell compartment is increased in EGFR-deficient papillomas

One or 24 h after injection of BrdUrd, mice were sacrificed, and papillomas were removed, fixed, sectioned, and immunohistochemically stained for BrdUrd as described in “Materials and Methods.” Unlabeled basal cells and BrdUrd-labeled cells in the suprabasal and basal compartments were counted in at least 10 randomly selected microscopic fields in each BrdUrd-stained tumor. At least 600 basal cells were counted in each of at least four tumors per genotype and time point. Labeling indices for basal, suprabasal, and total BrdUrd-labeled cells were calculated by dividing the number of BrdUrd-positive cells in each compartment by the total number of basal cells. Data were counted twice by two separate individuals. Data are reported as mean ± SE. The experiment is representative of two experiments that were performed.

GenotypeTime since BrdUrd injection (h)BrdUrd-labeled nuclei per 100 basal cellsa
BasalSuprabasalTotal
EGFR −/−138.2 ± 2.437.4 ± 4.575.6 ± 6.8
EGFR+/+141.3 ± 6.927.8 ± 2.7b69.1 ± 9.3
EGFR −/−2431.0 ± 1.1c78.1 ± 6.0c109.1 ± 7.1
EGFR +/+2441.6 ± 4.472.0 ± 6.3c113.6 ± 10.2
  • a The number of BrdUrd-labeled nuclei present in a field of 100 basal cells.

  • b Mean is significantly different from that of the corresponding EGFR −/− time point.

  • c Mean is significantly different from 1 h time point, where P ≤ 0.05 using Student’s t test.