Airway smooth muscle is fundamental for maintaining airway tone. The specialized ultrastructural features and regulatory mechanisms of airway smooth muscle are vital for normal airway function. Previous studies have shown that airway smooth muscle undergoes phenotypic changes during development and in various respiratory disorders. Airway smooth muscle may also mediate the immune response by secreting cytokines and chemokines. Cultured tracheal smooth muscle cells (TSMC) express three p21-activated kinase (PAK) isoforms which may promote TSMC migration by signaling to p38 MAPK. TSMC proliferation is an important component of airway remodeling in asthma and is consequently a target for the development of novel anti-asthma agents. HTSMC from ScienCell Research Laboratories are isolated from human trachea. HTSMC are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HTSMC are characterized by immunofluorescence with antibodies specific to α-smooth muscle actin. HTSMC are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast and fungi. HTSMC are guaranteed to further expand for 15 population doublings under the conditions provided by ScienCell Research Laboratories. Recommended Medium It is recommended to use Smooth Muscle Cell Medium (SMCM, Cat. #1101) for culturing HTSMC in vitro.