Star-forming ratio as a function of r for galaxies in four different M_* ranges (different panels). The red line represents galaxies that are embedded in substructures with at least two galaxies with log M_*(M_⊙) > 10.15. The black line represents single galaxies that orbit the cluster alone. Central BCGs are excluded. The coloured bands represent the 68% confidence intervals obtained with Poisson statistics (see Sect. 3).