Uridine 5′-triphosphate (UTP) is synthesized from uridine 5′-diphosphate (UDP) in the presence of the enzyme nucleoside diphosphate kinase (NDPK). Plant cells have high uridine as UTP. UTP on amination results in the generation of CTP and is catalysed by enzyme CTP synthetase. UTP acts on the purinergic?(P2Y2) receptor and mediates smooth muscle cells (SMCs) mitogenic activation. It also modulates osteopontin expression in SMCs. UTP is a sputum inducer and a promising candidate for assessing the inflammation in respiratory airway.