Fig. 3. Cell proliferation is similarly reduced in PTHrP^-/- and PTHrP^-/-;Ptch1^c/-;Col2a1-Cre mutant cartilage. (A) Comparison of BrdU-labeled chondrocytes in the cartilage of different mutants and in the wild-type control. Boxed regions are shown at higher magnification in the lower panel. The highly proliferating columnar chondrocytes (bracket) were reduced in the PTHrP^-/-;Ptch1^c/-;Col2a1-Cre mutant. (B) Percentage of BrdU-labeled chondrocytes in the columnar regions (circled in A), calculated from three independent samples to get the mean±s.d. Student's t-test, P<0.05.