Fig. 5. Variation in the normoxic level of hypoxia-inducible factor 1 (HIF) in crucian carp Carassius carassius. Data from Rissanen et al. (Rissanen et al., 2006). It is likely that the three bands in the gel are HIFs with different levels of phosphorylation. While some of the individual variation can be explained by variations in fish mass, most variation remains unexplained.