RAC2 and respiratory system disorder: In bronchial biopsies, an extracellular matrix (ECM) organisation pathway, including fibulin-1 and latent transforming growth factor binding protein 2 (LTBP2) genes, functionally involved in tissue remodelling in respiratory diseases [23, 24], was upregulated in RAC2 compared with RAC1 (p<0.02) and RAC3 (p<0.04) (table 4, supplementary table S16 and supplementary figure S5a).