Objective To assess the atherogenicity of lipoprotein(a), the effect of the heterogeneity of lysine binding of apolipoprotein(a) [apo(a)], a plasminogen-like glycoprotein component on the proliferation of human arterial smooth muscle cells (SMCs).Results Apo(a) wt-kringle IV-10 that has lysine binding properties possessed a growth-stimulating activity to SMCs on a dose-dependence manner by stimulating cells in the G1/G0 phase of cell cycle to S and G2/M phase, and reduced significantly the amounts of endogenous active TGF-β1 in culture when compared with the control medium and the GST group (2.4±0.5 vs 8.6±1.6 and 9.1±1.7 ng/ml, P