Luminosity function of galaxies in groups. The solid line is the luminosity function for semi-analytical galaxies in groups with virial masses higher than 10^13.5h^-1ℳ_⊙ and whose brightest galaxy is an elliptical galaxy. Grey region show the results for galaxies in groups in the SDSS DR7 obtained by Zandivarez & Martínez (2011). Upper and lower arrows represent the faint end slope of the luminosity function obtained by Popesso et al. (2005) and Zarattini et al. (2015), while middle arrow correspond to the value obtained in this work.