emission; the galaxy assembly and star formation histories derive directly from the hierarchical growth of structures. In addition, such models allow for a thorough statistical analysis. The model galaxies are obtained with the semi-analytic model by Croton et al. (2006), with the spectro-photometric model (including dust absorption and emission) described in Tonini et al. (2012). We implement the prescription for the galaxy rotation curves by Tonini et al. (2011), where the velocity profile is determined by the mass distribution of all galaxy components (dark matter, stellar disk and bulge, and gas), and the total circular velocity is $$V_{\rm C}^2(r)=V^2_{\rm DM}(r)+V^2_{\rm disk}(r)+V^2_{\rm bulge}(r) 
\label{Vc}$$ Each of the velocity terms in the equation is of the type $V^2 \propto G \ M(r)/r$ where $r$ is the galactocentric radius and $M(r)$ is the mass profile: a truncated isothermal sphere for the dark matter halo, a flat exponential disk, and a Hernquist (1990) profile for the bulge (see Tonini et al. 2011 for a complete description; see also Tonini et al. 2006a, Salucci et al. 2007). The slope of the TF relation in models, and in particular its tilting with galaxy type observed in the data, is the manifestation of the connection between galaxy 