TG and central nervous system cancer: In our previous studies, we showed that increasing PEG substitution can lower the binding affinities of different therapeutics.38–41 In earlier in vitro studies, we showed that 3 rodent glioma cell lines proliferated in response to thyroid hormone that is blocked by tetrac.26 Beyond antiproliferation at the level of the tumor cell, a second important facet of the properties of αvβ3 antagonists is that they have anticancer efficacy by multiple mechanisms.