IGF1R and neoplasm: In addition, the small leucine-rich repeat proteoglycan of bone extracellular matrix tissue biglycan, which is correlated with an aggressive phenotype of osteosarcoma, supported tumor growth and induced resistance to chemotherapy drug doxorubicin by forming a complex with IGF-1R leading to activation of the IGF-1R signaling pathway in human osteosarcoma cell line MG63 (37).