Id4 regulates p53 expression and cellular localization. Analysis of p53 protein (A) expression in L, L-Id4, D and D + Id4 cells. The western blot analysis shown in panel A is the representative of three different experiments. B. Immuno-cytochemical localization of p53 in L, L-Id4, D and D + Id4 cells. Nuclear and cytoplasmic (arrows) expression of p53 is clearly evident in L, L-Id4 and D cells. Whereas p53 is primarily nuclear in D + Id4 cells (arrows). Red: p53, Blue: DAPI. Representative images are shown.