Expression of messenger RNA for ITGA2 (A) and ITGB1 (B) were measured by real-time qPCR of cells cultured on TCPS, PEEK, smooth titanium alloy (sTiAlV), or rough titanium alloy (rTiAlV). Expression is normalized to GAPDH. *p<0.05, versus TCPS; #p<0.05, versus PEEK; $p<0.05, versus sTiAlV. TCPS, tissue culture polystyrene; BMP, bone morphogenetic protein; qPCR, quantitative polymerase chain reaction; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; PEEK, poly-ether-ether-ketone; sTiAlV, smooth Ti6Al4V; rTiAlV, roughened Ti6Al4V.