Noggin loaded and released from HGC maintains its biological activity. (A) HGC-Noggin maintains the ability to form dimers as determined by Noggin WIB under non-reducing conditions. (S0): native Noggin; (S4): Noggin loaded to HGC. (B) Noggin released from HGC inhibits Smad-1,5,8 phosphorylation. HGC-Noggin, HGC-BSA, HGC alone were incubated for 48 hours in SF medium that was collected, dialyzed and used to treat limb mesenchyme micromasses for 20 minutes. a, control medium; b, medium from HGC alone; c, medium from HGC-BSA; d, medium from HGC-Noggin; e, 200 ng of native Noggin