Six transmembrane protein of prostate (Stamp) proteins play an important role in 
prostate cancer cell growth. Recently, we found that Stamp2 has a critical role 
in the integration of inflammatory and metabolic signals in adipose tissue where 
it is highly expressed and regulated by nutritional and metabolic cues. In this 
study, we show that all Stamp family members are differentially regulated during 
adipogenesis: whereas Stamp1 expression is significantly decreased upon 
differentiation, Stamp2 expression is increased. In contrast, Stamp3 expression 
is modestly changed in adipocytes compared to preadipocytes, and has a biphasic 
expression pattern during the course of differentiation. Suppression of Stamp1 
or Stamp2 expression both led to inhibition of 3T3-L1 differentiation in concert 
with diminished expression of the key regulators of adipogenesis - 
CCAAT/enhancer binding protein alpha (C/ebpα) and peroxisome 
proliferator-activated receptor gamma (Pparγ). Upon Stamp1 knockdown, mitotic 
clonal expansion was also inhibited. In contrast, Stamp2 knockdown did not 
affect mitotic clonal expansion, but resulted in a marked decrease in superoxide 
production that is known to affect adipogenesis. These results suggest that 
Stamp1 and Stamp2 play critical roles in adipogenesis, but through different 
mechanisms.