Global gas metallicity as a function of the stellar mass (MZR) colour-coded with the LW-stellar metallicity measured at 1 R_e (LW–[Z/H]_Re, left panel), and with the SFR (right panel). Salmon squares represent the median Z_g values in ten mass bins. The averaged-binned values were fitted with a spline function (solid salmon lines). The insets show a scatter plot Z_g vs. LW–[Z/H]_Re (left) and Z_g vs. SFR (right) for the galaxies in the mass bin 9.2 ≤ log(M_⋆)≤9.4, which is marked with vertical dashed lines in the main figure. The solid brown lines represent an ODR fit to the scatter points. The Pearson correlation coefficient r is also displayed.