Charges fly in $1bn hormone patent battle.

Describes progress in the legal case in which the University of California, San Francisco, alleges that Genentech Inc. infringed on its patent for DNA for human growth hormone. Hormone leading to the development of the drug Protropin; Views of Genentech executives about the case; Details about key testimony; Problems with a paper published in `Nature' related to the case; Colleagues who have had to tesify against one another. INSET: Who's telling the truth about crucial plasmid?.