The present inventions provide eukaryotic cells, such as mammalian cells, that comprise adeno-associated virus (AAV) polynucleotides, including AAV capsid proteins (Cap), and are capable of expressing the polypeptides encoded by the AAV polynucleotides, and thereby are capable of producing AAV, including recombinant AAV. The eukaryotic cells also may comprise adenovirus (Ad) polynucleotides. The present inventions also provide methods of expressing AAV polynucleotides, as well as Ad polynucleotides, in eukaryotic cells, such as CHO cells, HEK 293 and BHK cells. The present inventions further provides other products and methods described herein.