FN1 and asthma: To understand the effect of RBM proteins (collagen-I, -III, and fibronectin) associated with repair and asthma compared to normal RBM proteins (laminin, collagen-IV) on basal airway epithelial functions, we used Electrical Cell-substrate Impedance Sensing (ECIS), which is a continuous, label free, impedance-based method that enables the study of cell attachment, spreading, and barrier function in the sub-nanometer range (25, 26).