EXT1 and asthma: Exostosins 1 and 2 are ubiquitous [14] predominantly present in the lung and are thought to be involved in vascular development and angiogenesis in endothelial cells of adult lung.[15] A role of EXT1 in asthma has also been suggested by Nonaka et al in an EXT1 knockout mouse model of asthma.[16] However, the role of EXT genes and exostosins in lung development and pathology remains to be elucidated.