October 21, 1983
Dear Phil:
I thought you might be interested in the enclosed manuscript describing secondary mutations in the provirally-mutated c-myc alleles we have cloned from bursal lymphomas. I'd be curious to know whether you've encountered any somatic mutations in translocated c-myc alleles.
We are in the process of trying to work out some biological assay for these mutant alleles, using several cell types, including fresh bursal cells to be returned to chemically-bursectomized birds.  In view of the obvious uncertainties, we are playing with all available technologies for getting DNA into lymphocytes; I appreciate the help we've gotten from Hunt Potter, whose electroshock method was mentioned to me by a graduate student formerly at Harvard.  If and when we obtain anything interesting with this approach, I will let you know.
With best regards,
Harold E. Varmus, M.D.