HGF and obstructive sleep apnea syndrome: The aim of the present review is to summarize the actual knowledge of proteins, genes, and nucleic acids implicated in the process of canine OSA metastasis, such as p63, signal transducer and activator of transcription 3 (STAT3), Snail2, ezrin, phosphorylated ezrin-radixin-moesin (p-ERM), hepatocyte growth factor-scatter factor (HGF-SF), epidermal growth factor receptor (EGFR), and miR-9 and miR-34a (Figure 2), as they may act as biomarkers or play an important role in targeted drug delivery.