Figure 4. UBF loss induces selective Caspase 3 cleavage in transformed iMEFs cells.

A. Ubf^fl/fl/Er-cre^+/+/Sv-T and Ubf^wt/wt/Er-cre^+/+/Sv-T iMEFs and B. Ubf^fl/fl/Er-cre^+/+ and Ubf^wt/wt/Er-cre^+/+ MEFs were assayed for activation (proteolytic cleavage) of Caspase 3 immediately before and at time points after treatment with 4-HT. In B) “iMEF+Staurosporin” refers to the extract from iMEFs cells treated with 1 μM Staurosporin used in A, and allows a direct comparison of p17 and p53 levels in iMEFs with those in primary MEFs. C. Electrophoretic fractionation on 1.5% agarose of genomic DNA recovered from Ubf^fl/fl/Er-cre^+/+/Sv-T and Ubf^wt/wt/Er-cre^+/+/Sv-T iMEFs at different times post tamoxifen treatment (pHT). In A) to C), recombination and UBF protein levels were assayed in parallel with each analysis and closely followed those shown in Figure S2B and S2C.