XXXX administration to @entity19 .

@entity172 @entity25609 @entity440 @entity19 @entity25608 @entity134
The strategy of fusing a protein of interest to a hormone-binding domain (HBD) of a @entity134 hormone receptor allows fine control of the activity of the fused protein. Such fusion proteins are inactive in the absence of ligand, because they are complexed with a variety of intracellular polypeptides. Upon ligand binding, the receptor is released from its inhibitory complex and the fusion protein becomes functional. In the @entity19 @entity172 receptor (ER) fusion system, proteins are fused to the HBD of the ER. The system relies on the use of a mutant ER known as ER(TAM). Compared to the wild-type HBD, ER(TAM) has 1000-fold lower affinity for @entity172 , yet remains responsive to activation by the synthetic @entity134 @entity25608 ( @entity25609 ). Because @entity25609 is expensive, animals can be treated with the cheaper precursor @entity440 , which is converted into @entity25609 by a liver enzyme. Here we present an overview of the methods used to deliver @entity440 to @entity19 . The most used method is intraperitoneal injection, because the amount of administered compound can be better controlled, but delivery by oral gavage is also possible. For short-term and immediate-effect studies or when conversion of @entity440 by the liver is to be avoided, @entity25609 can be used directly.
