Inhibits CBL-SH3KBP1 complex mediated down-regulation of EGFR signaling by sequestration of SH3KBP1. Binds to SH3KBP1 and prevents its interaction with CBL and inhibits translocation of SH3KBP1 to EGFR containing vesicles upon EGF stimulation. Monomer (By similarity). Interacts with CUL3; interaction is direct and forms a 5:5 heterodecamer (By similarity). Interacts (via PXXXPR motifs) with SH3KBP1 (via SH3 domains) (PubMed:11152963). Directly interacts with cathepsin B/CTSB (By similarity). Belongs to the KCTD3 family.