To be more specific, PGs conferred resistance to tumor therapy by activating key signals such as activation of EGFR-AKT signaling by versican, inducing breast cancer self-renewal [256] and chemotherapy resistance [49], activating NF-κB signaling by biglycan to promote resistance to chemotherapy of colon cancer [43] and activating the EGFR pathway by syndecan-1 to lead to chemoresistance in colon cancer [257]. Here, EGFR is linked to breast cancer.