The oxygen concentrations was controlled with a multi gas incubator MCO-5MUV (Sanyo) by N₂ substitution. Fluorescence confocal microscopy images were acquired using a Leica Application Suite Advanced Fluorescence (LAS-AF) instrument equipped with a TCS SP5 and 40× or 10× objective lens. Gain and pinhole values were set at 150% and 95.0 m (Figures ) or 68.0 m (Figure ).