This “oxygenation heterogeneity” was later confirmed by studies using chemical oxygen probes and the detection of transcripts or proteins induced by hypoxia at the particular tumour areas (e.g., CA9, VEGF, ANGPT2, EPAS1), with the rest of the tumour being relatively well-oxygenated [20,21,22]. The gene discussed is ANGPT2; the disease is neoplasm.