CDC42 and idiopathic pulmonary fibrosis: As a recent excellent example, Sainz de Aja and Kim (2020) and Wu et al. (2020) found that in idiopathic pulmonary fibrosis (IPF, the most common type of lung fibrosis), loss of Cdc42 function in alveolar stem cells (AT2 cells) results in impaired alveolar regeneration and consequently exposes AT2 cells to sustained elevated mechanical tension.