Left panels: [N II]λ6584/Hα versus the equivalent width of the Hα line for different galactocentric distance cuts (from top to bottom): < 0.25 kpc, between 0.25 and 0.5 kpc, between 0.5 and 1 kpc, and > 1 kpc. The dashed line marks the boundary proposed by Stasińska et al. (2006) to distinguish between star-forming regions (labelled SF) and AGNs. The dotted line indicates the boundary established by Kewley et al. (2006) to separate, within the AGN area, Seyferts from LINERs (labelled L). The dash-dotted line separates the region populated by lines produced in RGs proposed by Cid Fernandes et al. (2011). Right panels: [N II]λ6584/Hα versus velocity dispersion of the Hα line for the same galactocentric distance cuts. In all panels, the size of each point depends on the S/N measured at the peak of the [N II]λ6584 line. Grey dots in the background correspond to all points in the sample.