Cucumber aquaporin gene, CsPIP1;1 and figleaf gourd aquaporin gene CfPIP2;1 were injected to $Xenopus$ oocytes in order to study water transport activity. While CsPIP1;1 did not transport any water and was not responsive to mercury, oocyte injected with CfPIP2;1 rapidly increased their volume without saturation indicating active water transport. Calculation of water permeability of oocytes clearly distinguished the two genes. In response to exogenous application of $H_2O_2$, only CfPIP2;1 responded, reducing osmotic water permeability. Transgenic $Arabidopsis$ plants overexpressing aquaporin genes did not respond to applied $H_2O_2$.