Inactivation of FAM20B altered the collagen composition of AF. (A, B) In situ hybridization analyses of Col I mRNA in the IVD of 3-week-old control and cKO mice. A1 and B1 were the higher magnification views of the black boxes in A and B, respectively (Bars in the A, B = 200 μm, Bars in the A1, B1 = 50 μm). (C, D) In situ hybridization analyses of Col II mRNA in the IVD of 3-week-old control and cKO mice. C1 and D1 were the higher magnification views of the black boxes in C and D, respectively (Bars in the C, D = 200 μm, Bars in the C1, D1 = 50 μm). A–D was the representative images of at least 3 mice for each group. (E, F) QRT-PCR analyses of Col I and Col II mRNA in 3-week-old mice showed that the Col I mRNA level was significantly lower and Col II level was much higher in the AF of cKO mice than in the control mice (n = 6, * = p < 0.05).