Effects of RGD, KRSR, and KSSR on TGF-b1 levels in osteoblast-likeMG63 cells. Levels of latent and active TGF-β1 were increased on PLL-g-PEG surfaces vs. TCPS and SLA surfaces (a,c). KSSR did not affect active or latent TGF-β1 levels. Addition of 1.26 pmol/cm2 RGD reduced latent and active TGF-β1 levels, as did addition of 15 pmol/ cm2 of KRSR (b,d). (a,c) *P<0.05, Ti surfaces vs. plastic; **P<0.05, PEG surfaces vs. SLA. (b,d) +P<0.05 , RGD vs. KRSR alone (0 RGD); ‡P<0.05, KRSR vs. RGO alone (0 KRSR).