Reappraisal of L-canavanine as an anti-tumour agent.

L-canavanine, an analogue of L-arginine, is known to have a toxic effect on pathogens. In experiments performed on a specialised epithelial-like cell system which is conditionally transformable, L-canavanine appeared to exhibit (1) a reversible 'static' effect on exponentially growing cells at optimal concentration, and (2) a selectively toxic effect on proliferating cells. The capacity to recognise 'tumour cells' in a heterogeneous population of cells is of potential interest in cancer chemotherapy.