p53 ablation is critical for MCV sT transformation of MEF cells.

<p>(A) MCV sT induces soft agar colony formation in the absence of p53 in MEF cells. MEF cells isolated form <i>Ubc</i>^{<i>CreERT2</i>}<i>; ROSA</i>^<i>sT</i>, <i>ROSA</i>^<i>sT</i>, <i>Ubc</i>^{<i>CreERT2</i>}<i>; p53</i>^{<i>flox/flox</i>} and two <i>Ubc</i>^{<i>CreERT2</i>}<i>; ROSA</i>^<i>sT</i><i>; p53</i>^{<i>flox/flox</i>} embryos from littermate were treated with 500nM 4OHTMX over 7 days, and cells were subjected to soft agar colony formation assay. Asterisks(*) indicate statistical significance <i>p<0</i>.<i>05</i>. (B) Soft agar colonies induced by p53 ablation. p53 ablation alone did not lead to colony formation. (C) Expression of MCV sT in MEFs from <i>Ubc</i>^{<i>CreERT2</i>}<i>; ROSA</i>^<i>sT</i><i>; p53</i>^{<i>flox/flox</i>}.