Clone
SP2 has been established to work in formalin-fixed, paraffinembedded tissues.
The presence of PR in breast tumors indicates an increased likelihood of
response to anti-estrogen (tamoxifen) therapy. Staining patterns observed
include: ER+ and PR+, ER+ and PR-, ER- and PR+, and ER- and PR-. The SP2 clone
is a high affinity rabbit monoclonal. An in-house study showed that SP2 clone
had a much higher affinity as compared to mouse monoclonals for the progesterone
receptor. Studies have also shown that the SP2 clone provides supplementary
evidence to ER in predicting survival. Excellent results can be achieved with
antigen retrieval at lower temperatures such as 80 or 95 degrees Celsius. The
robustness of SP2 is further proved by the fact that in some instances staining
can be obtained even without antigen retrieval. Thus, SP2 may prove of greater
value than ER as a prognostic indicator in human breast
cancer.