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. 2003 Oct 27;100(23):13344–13349. doi: 10.1073/pnas.2234026100

Fig. 4.

Fig. 4.

(A) In continuous passage, loss of Igf2 in BP-MEFs results in their senescence and eventual death. Igf2-/- A-MEFs have a short lifespan in culture and cannot be propagated (arrow). (B) Transduction of MEFs with an Igf2-expressing retroviral vector results in a significant production of IGF2. Total cell protein (50 μg) was added per lane. The marker lane was loaded with 1 μg of recombinant Igf2 and the gel hybridized with a mouse-specific Igf2 antibody (Amano). (C) Infection of P-MEFs with the Igf2 vector enhances their growth rate and viability compared with control (Gfp-infected) cells. (D) Transduced Igf2 also had a similar enhancing effect on proliferation on the Igf2-deficient BP-MEFs. (E) BP-MEFs (passage 3) infected with the Igf2 vector and plated at clonal density (1,000 cells per 150-mm dish) show an ≈150-fold increase in colonies compared with control infections. This assay was repeated five times.