S100A4 and lung disorder: Importantly, the S100A4 distribution-related differences in both NMII-A and NMII-B were limited only to pathophysiologic range substrate stiffnesses that exist under conditions of fibrotic lung disease (8–25 kPa), and the effects of S100A4 loss were lost on standard tissue culture substrate stiffnesses (106 kPa) (Fig. 3, G and H).