Subject: Psn9, Psn143, Psn145 and Psn227 The following information was provided by Annette Parks of Exelixis, Inc. (5/04). Psn9 was induced with EMS and results in a L499Q change in the 541 amino acid Psn isoform. It appears to be hypomorphic. Psn143 is a deletion and/or splice site mutation resulting in deletion of the amino acids between the first transmembrane domain and the middle of the fourth transmembrane domain. It behaves as a null allele. Psn145 results in loss of amino acids 51 to 105. Psn227 results in a change of Q41 to stop.