Abl knockout attenuates airway resistance and contraction of tracheal rings in the animal model of asthma. (A) Abl-lox and Ablsm−/− mice were sensitized and challenged by OVA. Airway resistance (RAW) in these mice was evaluated using the FlexiVent system. RAW in Abl-lox mice treated with OVA was higher than in Abl-lox mice treated with PBS, verifying the development of AHR in the mouse model. RAW in Ablsm−/− mice treated with OVA was reduced compared to Abl-lox mice treated with OVA (n = 10–14, *P < 0.05). (B) The contractile response of tracheal rings from these mice was determined by using an in vitro organ bath system. Contractile force is normalized to maximal force of rings from OVA-treated Abl-lox mice. Contractile force of OVA-sensitized and challenged Abl-lox mice was increased as compared to naïve Abl-lox mice. OVA-induced airway smooth muscle contraction was reduced in Ablsm−/− mice (n = 10–14, *P < 0.05).