These results could be explained by the existence of a possible mechanism for inhibition of PPF in the less oxygenated areas that are typical of the quiescent osteoblastic niche.
For these reasons, cells are forced to adapt immediately to the reduced pO2 levels when entering these low oxygenated areas.
EGFR expression was namely predominantly present in oxygenated areas and there was a relatively low overlap between EGFR and pAKT expression in vivo.
Now, transition zones between anoxic and oxygenated areas are exactly the places where these two metabolic hypotheses would place the origin of eukaryotes.
The expression of HIF-1 responsive genes, including BNIP3, has been shown to be elevated in malignant melanoma as a result of a constitutive HIF-1 activity harbored by these cancer cells even in oxygenated areas of the tumors.
When oxygen tension drops during, for example, chronic obstructive pulmonary disease, a response known as hypoxic pulmonary vasoconstriction (HPV) occurs, diverting the blood flow to the higher oxygenated areas to match ventilation to perfusion.
This could become necrotic in less oxygenated areas and descend along the musculoaponeurotic system of the forehead to reach the superior orbital rim or lateral orbital rim, developing adhesions, fibrosis, and chronic inflammation, to ultimately form a cicatrix.
In this relationship, glycolytic hypoxic cancer cells convert glucose to lactate, which is taken up by cells that convert lactate to pyruvate for oxidation by mitochondrial respiration in oxygenated areas of the tumor [ 6].
Figure 8 shows that if the distance from a thrombotic vessel to the nearest functional vessel is short enough, the cells arrive to better oxygenated areas without experiencing severe hypoxic stresses (thus diminishing their death) and reducing the palisade lifetime.
The presence of metazoan meiofauna under permanently anoxic conditions has been reported previously also from the deep-sea sediments of the Black Sea, although these records were interpreted as the result of a rain of cadavers that sunk to the anoxic zone from adjacent oxygenated areas [ 20].
