Figure 3. PTEN overexpression results in reduced growth rate in culture, resistance to oncogenic cellular transformation, decreased c-Myc levels, and confers cancer resistance in vivo.

a, Growth curves of wt and tg MEFs (n=3 per genotype). b, serial 3T3 cultivation of primary wt and tg MEFs (n=3). The figure shows the accumulated population doublings (PDL) at each passage. c, Colony-formation efficiency of wt and tg MEFs (n=4). d, Transformation susceptibility of wt and tg MEFs (n=4). The picture shows the numbers of neoplastic foci formed after transfection with a combination of oncogenic Ras and E1A. e, Susceptibility to 3MC-induced fibrosarcomas. Mice of the indicated genotypes were injected intramuscularly with 3MC in one of the rear legs and the latency for the development of fibrosarcomas was scored (line 3, n=5 per genotype). Super-PTEN mice developed tumors with a significantly longer latency than wild-type mice, as determined by Gehan-Breslow-Wilcoxon test (*p<0.05). Western blot shows PTEN expression levels in tumors derived from wild-type and Super-PTEN mice. f, Soft-agar assay in primary MEFs transformed by E1A+Ras (top) or cMyc+E1A+Ras (bottom). The graph shows the number of colonies per well (six-well plates, triplicate samples). A representative picture from the assay is showed. g, Immunoblotting of protein lysates from wt and tg MEFs and tissues. Total cell extracts were probed with antibodies towards c-Myc, PTEN and β-actin. Error bars in a, b, c, d and f denote s.d. See also Figure S2.