RAPGEF5 and head and neck squamous cell carcinoma: To test the functional antagonism of the FER PROTACs, EGF or HGF-stimulated invasion assays were performed on all HNSCC PDO models (T1, T4, T5 and T8), which showed that both 008 and 039 effectively prevented GFR-dependent invasive growth (Fig. 6C and 6D and Supplemental Fig. 7A and 7B).