Radial profile of the SFR (left) and molecular gas fraction (right) (normalised to R₂₅) for NGC 628 (red squares), M 101 (black circles) and M 33 (green diamonds). SFRs were derived using FUV (GALEX) and TIR luminosities (see Eq. (1)). The molecular gas fraction was derived from HI and CO observations assuming a X_CO factor inversely proportional to the metallicity (see Vílchez et al. 2019, for more details). The elliptical rings have a width of 0.1 R₂₅. Data points and coloured areas correspond respectively to the mean value and the dispersion for each ring.