The mRNA and protein expression of p300 in NPCs and nonneoplastic mucosal tissues. A. Up-regulated expression of p300 mRNA was examined by RT-PCR in 4/4 NPC cases, when compared with n nonneoplastic mucosal tissues. B. Up-regulated expression of p300 protein was detected by Western blotting in 4/4 HCC cases, when compared with nonneoplastic mucosal tissues. C. High expression of p300 was observed in a NPC, in which more than 90% tumor cells revealed positive immunostaining of p300 in nuclei (upper panel, ×100). D. A NPC case demonstrated low expression of p300, in which less than 5% of tumor cells showed immunoreactivity of p300 protein in nuclei (upper panel, ×100). E. The nonneoplastic mucosal tissue showed nearly negative expression of p300 protein (upper panel, ×100). The lower panels indicated the higher magnification (×400) from the area of the box in C., D., and E., respectively.