Bottom panels: show the distribution in the plane galaxy stellar mass vs. (U−B) rest-frame color (and vice versa) of all the galaxies of the Wall sample. Each galaxy is color coded according to the environment in which it resides: moving from blue to red and black, galaxies are located in progressively denser environments. Top panels: normalized distribution in (U−B) rest-frame colors (on the left) and in galaxy stellar masses (on the right) of these three samples. Moving from lower to higher densities clearly results both in redder rest-frame color distributions and in stellar mass distributions skewed toward higher masses.