RHO and neoplasm: Although the exact regulatory mechanisms and the actions of AQP1 on intracellular signalling pathways are yet to be fully uncovered, hypoxia appears to be one of the inducers of AQP1 over-expression in tumour cells, in combination with important downstream effectors including β-catenin, FAK and the Rho family of GTPases known for their role in tumorigenesis.