NTRK1 and obstructive sleep apnea syndrome: In the first study, in vitro and in vivo experiments were conducted to (1) evaluate TrkA mRNA and protein expression in canine OSA cell lines, (2) study the mitogenic and antiapoptotic effects of TrkA signaling in canine OSA cell lines, and (3) determine whether spontaneous canine OSA samples derived from primary tumors or lung metastatic lesions express the TrkA receptor.