NUV- (top) and FUV-based (bottom) specific star formation rate vs. stellar mass relation for the sample of optically red spirals. Filled and empty circles show 22 μm detections and non-detections, respectively. For non-detections, the SFR has been determined by assuming a 22 μm flux density equal to zero (left panels) or to 3 mJy (i.e.,  ~3σ WISE detection limit; right panels). The dotted and solid lines show the best fit to the star-forming sequence obtained by Salim et al. (2007) by including only star-forming galaxies (i.e., excluding galaxies with optical lines ratios typical of active galactic nuclei) or all galaxies with NUV − r colour lower than 4, respectively.