Figure 3.

Hemoglobin levels in elutriated G₁, S, and G₂ cell fractions of doxycycline-treated p21 MEL cell transfectant cells. p21 MEL transfectant cells (clone p21.12) were treated with doxycycline for 36 h, and cells were separated by size by centrifugal elutriation as described in Materials and Methods. Elutriated cell fractions were analyzed by fluorescence-activated cell sorter scan, and fractions representing G₁ [66(3)], S [90(1)], and G₂/M [98(2)] were resuspended at 1 × 10⁵ cells per ml in normal growth medium and incubated at 37°C for the indicated number of days. Extracts were prepared and analyzed by nondenaturing PAGE and immunoblotting for hemoglobin (Hb). The levels of hemoglobin in extracts of the parental MEL rtTA cell line treated for 7 days with 5 mM HMBA are indicated (Right).