IGF1 and neoplasm: Explanations for the potential tumor biological role of KLKs and their prognostic value mainly focus on their ability to cleave ECM proteins and to provoke activation/release of signaling molecules such as transforming growth factor (TGF-β), insulin growth factor-1 (IGF-1), epidermal growth factor receptor (EGFR), or the protease-activated receptors PAR1/2 [31].