FIG. 3.

ΔNp73 lacks in vitro transforming capacity in NIH 3T3 cells. NIH 3T3 fibroblasts were infected with a control retroviral vector (A) or a ΔNp73-expressing vector (B). After infection, cells were selected in puromycin for 3 days. ΔNp73-expressing NIH 3T3 cells fail to undergo morphological transformation and remained contact inhibited. Identical results were seen with three different lines of NIH 3T3 cells. (C) For comparison, spontaneously immortalized ΔNp73-expressing MEFs, subsequently transduced with H-Ras^V12 retroviruses, showed strong morphological transformation in vitro and were highly tumorigenic in vivo (see Table 1).