SMAD4 and neoplasm: Although it has already been shown by others that PDAC cell lines are able to form 3D spheroids, our results demonstrate that we could consistently reproduce tumor spheroids from PaCa DD183 and PANC-1 cell lines, as well as the newly generated SMAD4 knock-out cell line, PANC-1SMAD4 (−/−), to have a working platform for drug testing.