MZ relation (left panels) and FMR projection μ_0.32 (right panels) of the CALIFA galaxies in S17, rescaled to match the Maiolino et al. (2008) N2 calibration, for a correct comparison with M10 whose MZ and FMR projection for SDSS galaxies are shown as black lines. The CALIFA galaxies are shown with a colour code depending on their SFR, showing that higher SFR galaxies show lower metallicities at fixed mass, as predicted by the FMR. This secondary dependency is removed once the galaxies are plotted on the FMR μ_0.32 projection on the left. Lower panels: medians in each SFR and M_* bins and their 1σ dispersions, with the same colour code.