Use of the vertical rotor to facilitate estrogen and progesterone receptor analysis.

Sucrose density-gradient analysis is one method of identifying specific estrogen and progesterone receptors in mammary tumor tissue. Use of the vertical rotor makes this practical for routine applications in the clinical laboratory by increasing the number of samples that can be run at one time and shortening the centrifuge time from 18 to less than 2 h. The separations and reproducibility compare favorably with those obtained with a swinging-bucket rotor.