TGFA and posterior cortical atrophy: Aside from providing the most detailed ultrastructural analysis of NI in PCa, Bockman postulated a key role for the transforming growth factor alpha (TGF-α) in this process: invaded nerves demonstrated high immunoreactivity for the TGF-α, whereas PCa cells expressed high levels of epidermal growth factor receptor (EGFR), the natural receptor for TGF-α.