Primary bovine keratocytes were transfected with siRNA against HAS1, HAS2, or a combination as described under “Experimental Procedures.” The cells were cultured in serum-free medium for 48 hand then exposed to FBS and TGFβ for 48 h. A, HA in serum-free medium (left, open bars) or TGFβ-FBS (right, gray bars) was analyzed by HABP-ELISA as described “Experimental Procedures.” B, chondroitin/dermatan sulfate (CS) (gray bars) and HA (open bars) were analyzed by FACE gels similar to those in Fig. 1. Ctrl (control) shows HA and CS expression in serum-free medium for 48 h. All other samples show expression during 48 h after induction with TGFβ-FBS. Mock indicates no siRNA. HA and chondroitin/dermatan sulfate values are normalized to the Mock samples. Bars show standard deviation of triplicate analyses.