Fig. 6. Decreased epithelial and mesenchymal cell proliferation in Foxp2^-/-;Foxp1^+/- compound mutant lungs. Immunohistochemistry was performed using a Ki-67 antibody to detect proliferating cells in the lungs of wild-type (A) or Foxp2^-/-;Foxp1^+/- compound mutant (B) mice. Quantitation (C) shows that there is a more than 40% reduction in cell proliferation in both the epithelia and mesenchyme of Foxp2^-/-;Foxp1^+/- compound mutant lungs. Expression of cyclin D1 (D,E) is decreased in Foxp2^-/-;Foxp1^+/- lungs, whereas expression of the CDKI p57 (F,G) is increased. Scale bars: 50 µm.