I'm trying to inhibit a signalling pathway in a breast cancer cell line (MDA-MB-231) through overexpressing its physiologic antagonist via adenoviral infection. The problem I'm facing is the inconsistent inhibition between separate infections at the same MOI, some times I can get a good inhibition (more than 95%) and some times its below 10%. I have tried a few things like infecting cell in suspension vs adherent, incubation time (48-72 hours) to overcome this hurdle but still facing the same problem. I have no idea what is going wrong between the batches of infection or there is something else which need to be resolved first.