Knockout (KO) models have provided important insights into the function of
many receptors and signalling molecules. However, analysis of endothelin (E
T) receptor knockouts has been complicated by the development of lethal phe
notypes. In this paper, we present our strategy for examining endothclin-B-
(ETB) receptor function in the context of other strategies for rescuing the
lethal phenotype of ETB knockout mice.