Estrogen promotes SRC-1 and cyclin D1 expression and the proliferation of thyroid cancer cells, but knockout of SRC-1 did not abolish estrogen-induced cell proliferation; a study also revealed that 87% of anaplastic thyroid cancer patients were SRC-1-positive, and SRC-1 positivity was associated with reduced disease-free survival [101]. Here, SRC is linked to thyroid gland undifferentiated (anaplastic) carcinoma.