A few weeks or months, perhaps, before we decided to submit our paper for publication, I discovered that... that Ted Puck was giving a major lecture at the annual FASEB meeting in Atlantic City, New Jersey, just a few hours from Philadelphia. And the FASEB meeting, the Federation of the American Society of Experimental Biology, drew at least, in those days, 15,000 to 20,000 biologists. A huge meeting, and Ted Puck was giving a major address at this conference. And I... so I decided to go to this meeting.

I went to the meeting, entered the hall, a huge hall at one of the big hotels in Atlantic City, took my seat, listened to Ted Puck talk about his cultures of human cells and the major work that he was doing were efforts to understand their nutrient requirements. And he, even in his publications, described in very... in 13 point type, a font that's hardly legible, the methods that he used to screen all of the amino acid components and the serum components used in his culturing of human cells to be sure they didn't contain any toxic materials and to learn that they were beneficial for the cell culture, because he argues strenuously that these normal human cells were very fastidious and required utmost determination of optimum conditions for growth.

I, on the other hand, was using media purchased from commercial sources, never tested any further in my laboratory and I was using essentially off-the-shelf commercial material that was never studied in any way near what Ted Puck was doing and that was part of my worry. So after Ted got finished with his lecture, questions were requested and, with some fear, I raised my hand in this enormous hall and said, 'Dr Puck, in the course of your research with human cells, have you ever observed that the cells can be sub-cultured frequently and then suddenly lose their capacity for replication?' And without hesitation, he said, 'Oh, of course, we see this frequently but obviously it's because of our failure to determine, with the accuracy necessary, that the media components are without toxic components.'

And I sat down because it was then obvious to me that he had missed the whole point and that I was home free, essentially because what he had seen... and he went on to say, 'Furthermore, when that happens, we simply go back to our freezer and withdraw an ampoule of cells and continue our work', which, of course, made sense in respect to what he was doing but it confirmed what we had found. And that was a great relief.