Neutrophil differentiation induces TG2 expression both in the cytosol and the nucleus of NB4 cells. (A) Transglutaminase activity in cells lysates. Cells were treated with 1 μM ATRA for 7 days during which TG2 enzymatic activity was measured in their cytosolic and nuclear fractions. Activity was measured by detecting incorporation of [³H]putrescine into casein. The amount of incorporated [³H]putrescine was determined in a beta-counter. Bars depict the means of 3 separate experiments each performed in duplicate. Error bars indicate standard deviation (SD). (B) Western blot analysis of TG2 in NB4 cells. Cytosolic and nuclear fractions were separated by SDS-PAGE. Total protein (25 μg) was loaded in each lane, and blots were developed with CUB7402 monoclonal antibody against TG2.