FIG. 1.

HPV-18 URR-E7 does not prolong S phase in differentiated keratinocytes of raft cultures. (A) Schematic diagram of pulse-chase-pulse experiments with two TdR analogues. Cultures were pulsed with ³H-TdR for 6 or 12 h as indicated, chased for different durations, and then exposed to BrdU for the last 6 h or longer before harvest (downward arrow). The values at the top indicate hours before harvest, whereas those below indicate the ages of raft cultures in days after they were raised to the air-medium interface. The incorporation of BrdU and ³H-TdR was detected by immunohistochemistry (in red) and autoradiography (black dots), respectively. The percentages and numbers (in parenthesis) of doubly labeled cells among all ³H-TdR-positive cells in the differentiated strata are shown on the right. Positive cells along the entire section were scored. (B) Immunostaining of keratin 1 and autoradiography of ³H-TdR in T6/C0/B6 raft cultures. (C) Example of cells positive for ³H-TdR, BrdU, or both in T6/C0/B6 and T6/C42/B6 cultures.