Multiple extractions of hormone receptor from rabbit uteri and human breast tumors.

The cytosol hormone receptors were extracted from rabbit uteri and human tumors with tris buffer systems for three consecutive homogenization and centrifugation processes to obtain three cytosols C-1, C-2, and C-3. The assay results evaluated revealed that minimal to tremendous amounts of receptor activities were present in C-2 and/or C-3 fractions. The essential experimental conditions and some speculative mechanisms have been discussed in detail.