- A new model for disruption of the ornithine decarboxylase gene, SPE1, in Saccharomyces cerevisiae exhibits growth arrest and genetic instability at the MAT locus. Schwartz, B., Hittelman, A., Daneshvar, L., Basu, H.S., Marton, L.J., Feuerstein, B.G. Biochem. J. (1995)