Figure 4.
Uncoupling of differentiation and cell division in BCER and 3T3-L1 cells. (A) Quantitative evaluation of differentiating BCER cells (Left). Vector control BCER cells (○) and E7-expressing BCER cells (●) in the presence of estrogen (0.5 μM) or vector control BCER cells in the absence of estrogen (▴) were subjected to the standard differentiation protocol, and samples (days 5–8) were stained with Oil-Red-O. Dishes were scanned and the absorbance was plotted to determine adipocyte differentiation. Photographs (at ×40 and ×400 original magnification) were taken at day 8 to visualize characteristic fat accumulation. (Lower) Northern analysis of differentiating BCER cells. Five micrograms of total RNA per lane was examined by using a probe for the adipocyte-specific aP2/422 gene. (B) Quantitative evaluation of differentiating 3T3L1 cells. Vector control 3T3-L1 cells (○) or E7-expressing 3T3-L1 cells (●) were subjected to the standard differentiation protocol, and samples (days 4–10) were stained and evaluated as in A (Left). Photographs (Right) were taken from differentiating cultures at day 10 (×100). (Lower) RNA analysis of differentiating 3T3L1 cells. Five micrograms of total RNA per lane was examined as in A. (C) Differentiation of 3T3-L1 cells expressing HPV-16 E7 was induced by the standard protocol. Cells were stained with hematoxylin and Oil-Red-O after 7 (Upper) or 10 days (Lower) and examined microscopically for mitotic figures (×1,000).