A human cell line from a pleural effusion derived from a breast carcinoma.

Soule HD, Vazguez J, Long A, Albert S, Brennan M.
Journal of the National Cancer Institute. 1973 Nov;51(5):1409-16.
A primary culture, 734B, was grown from a pleural effusion of a patient with metastatic mammary carcinoma. This culture continually produced free-floating cells used to initiate serial passages that could be transferred at 25-day intervals. A stable cell line, MCF-7, was derived from the free-floating cells and has been maintained for over 90 weekly passages. MCF-7 and 734B retained several characteristics of differentiated mammary epithelium, including the cytoplasmic estrogen receptor and the capability of forming domes. Four lines of evidence attest to the human origin of the cells.