I will describe the general structure of supergravity on AdS5xS5 at one loop, and I will discuss aspects of the boostrap program for constructing multi-channel four-point correlators of arbitrary Kaluza Klein modes of the five-sphere. I will show how to overcome a number of complications that emerge when the general case is considered, and I will illustrate with non trivial examples that indeed there exists a unique one-loop correlator, up to a class of ambiguities, such that all 1/N^4 predictions coming from the OPE are correctly reproduced. Finally I will discuss in which way the success of this bootstrap program is also a non-trivial confirmation of quantum gravity within the AdS/CFT correspondence.