The key finding was that following 21 days post-lung lobe resection (PNX, a treatment known to exacerbate pulmonary fibrosis in Cdc42-null mice), the average Young’s modulus of the central regions in a fibrotic lung was ~3 kPa, while the fibrotic regions located within a 2 mm region of the lung periphery exhibited a Young’s modulus three times higher (~9 kPa), suggesting that this heterogeneity might drive the progression of pulmonary fibrosis from the periphery of lobes to the central regions (Figure 2B). Here, CDC42 is linked to pulmonary fibrosis.