Gradient’s slope (Δα) as a function of the disk metallicity of SF galaxies (stars) and AGN host galaxies (circles) with logM_*/M_⊙ >  10.5, color-coded according to the nuclear metallicity.Black and red contours represent density curves computed by a KDE. In the legend, we also report the Spearman rank-order correlation coefficient that supports the finding that the SF gradients are strongly correlated with the disk’s metallicity (sp_SF = 0.54), but the same is not true for the AGN host galaxies. Indeed, AGN hosts have on average steeper slopes than SF due to their higher nuclear metallicities.