Fig. 2. TGF-β1 stimulates COMP expression independent of high cell density.
(A) Induction of COMP mRNA precedes that of Col2a1 in monolayer BMSC. Primary human BMSC grown as monolayer culture to ~70% confluence was treated with TGF-β1 for the indicated time points. The mRNA levels of COMP and Col2a1 were measured as described above (mean with 95% CI, n = 3). P-values from Student’s t-test comparing COMP mRNA at time 0 to: 2 h (P = 0.0639), 4 h (P = 0.0051), 8 h (P = 0.0069), day 1 (P = 0.0213), day 3 (P = 0.0004), and day 14 (P = 0.0062). (B) TGF-β1 stimulates synthesis of COMP protein. Human primary BMSC grown in monolayer were treated with TGF-β1 for the indicated time points. The amounts of COMP protein recovered from cells and their associated extracellular matrix were detected by Western blot using a rabbit polyclonal anti-COMP antibody.