Effect of HNF4α on cell proliferation. MTS proliferation assay was performed over a time span of five days in cell line 19-2-2 (A) or cell line 19-2-6 (B). Cells were treated with 1 μg/ml doxycycline and/or 1 μM Shld1 at day 0 as indicated and the metabolic activity was determined at the given time points. The medium was not changed during the whole period. The assay was performed in 96 well plates with n = 3 measurements. Using the student's t-test p-values were calculated for doxycycline or Shld1 treatment compared to control: *p < 0.01. Similarly, p-values comparing double treated samples (doxycycline and Shld1) with doxycycline treated samples were computed: +p < 0.01. The results were confirmed in an additional independent experiment for each cell line. We did not observe any effects of doxycycline or Shld1 on cell proliferation of HEK293 cells without the HNF4α transgene.