Specifically, since previous studies from our group have shown that Insulin-like Growth Factor-1 Receptor (IGF-IR) plays a critical role in regulating β1 integrin expression and since the absolute levels of IGF-IR increase during PCa progression in TRAMP tumors [33-35], we propose that IGF-IR may be an upstream regulator of Trop-2/β1 integrin levels in metastasis-prone tumor types. This evidence concerns the gene IGF1R and posterior cortical atrophy.