EPAS1 and chronic rhinosinusitis with nasal polyps: To investigate HIF1α and HIF2α expression in NPs and control nasal mucosa, we collected IT biopsies from both controls and patients with CRSwNP, and NP samples from patients with CRSwNP for immunohistochemistry, generating three groups of samples: control inferior turbinate (IT (CONTROL)), IT from patients with CRSwNP (IT (CRS)), and nasal polyps from patients with (NP (CRS)).