It was indeed S-100, this is the best known adipocyte marker, specific for
adipocytes but many other cells as well. A quick Medline search yielded
leptin as a promising marker. Molecular markers like PPAR gamma 2, adipocyte
P2 (aP2), adipocyte determination and differentiation factor 1 (ADD1), and
fatty acid synthase (FAS) may be detectable by your moledular genetics labs,
I'm going to have to stick to S-100.

By the way, if you are looking for a marker for preadipocytes, use CD34- it
stains uncommitted fibroblasts in fat and most tissues. I believe they are
the source of many fatty tumors. If you want to see some nice pictures :

Silverman JS, Tamsen A. J Cutan Pathol 1997 Sep;24(8):484-93
Fibrohistiocytic differentiation in subcutaneous fatty tumors. Study of
spindle cell, pleomorphic, myxoid, and atypical lipoma and dedifferentiated
liposarcoma cases composed in part of CD34+ fibroblasts and FXIIIa+
histiocytes.


Jeff Silverman
Southside Hospital
Bay Shore New York