<prompt> Answer this question truthfullyWhat is the molecule that needs to be present for the insertion of aquaporin 2 channels in the luminal membrane of principal cells of the late distal tubule and collecting duct?  <response>: <reason> The molecule that needs to be present for the insertion of aquaporin 2 channels in the luminal membrane of principal cells of the late distal tubule and collecting duct is ADH. 