IGFBP7 and thyroid gland undifferentiated (anaplastic) carcinoma: Overexpression of IGFBP7 in two undifferentiated human anaplastic thyroid carcinoma cell lines, ARO and FRO, and one differentiated follicular human thyroid carcinoma cell line, WRO, significantly inhibits tumor proliferation both in vitro and in vivo, whereas knockdown of endogenous IGFBP7 in WRO cells substantially increases proliferation and tumor growth.