HNF4A and obstructive sleep apnea syndrome: We achieved this by: (a) determining if β-catenin is differentially expressed, with respect to both quantity and cellular localization, between canine OSA patient populations with increased and normal serum ALP concentrations; and (b) determining if cell lines derived from normal and increased serum ALP OSA tissue have differential β-catenin activity as determined by: (i) the nuclear localization of β-catenin, and (ii) TCF binding site reporter plasmid activity.