. (A) Expression levels of tTG on the surface of live untreated and TPA-treated cells were determined by immunostaining with 00 μg/ml polyclonal anti-tTG antibody and flow cytometry. (B) Transglutaminase activity on the surface of live untreated and TPA-treated cells was quantified by measuring cell-mediated incorporation of \[^0^H\]putrescine into N,N-dimethylcaseine. Bars 