(August 2003) In the beginning, there were chickens Surprisingly enough, our understanding of tumour formation has its roots not in humans, but in the chicken. For the past century it has been known that viruses can be causative agents of cancer. Cancer-causing elements were first described in viruses infecting poultry in 1909 [1]. Later, it was shown that the injection of these viruses was sufficient for tumour formation. But the molecular basis of cancer was unearthed only with the discovery of cellular homologues to these cancer-causing elements in 1976 [1]. When the viral DNA sequences were isolated and characterized they…