These include the secreted ligand insulin-like growth factor (IGF-1) [46], proteins known to be elevated in prostate cancer patient serum, such as inter-alpha trypsin inhibitor heavy chains 2 (ITIH2) [47,48] and 4 (ITIH4) [48], apolipoprotein A1 APOA1 [48,49], carnosine dipeptidase (CNDP1), whose folding state has been demonstrated to be altered in prostate cancer patient plasma [50], and DEFA1B/DEFA3, a defensin protein(s) whose cognate transcript levels in blood predict prostate cancer treatment response [51]. Here, IGF1 is linked to prostate cancer.