STAT3 and neoplasm: This also suggests that the suppressive effect of berberine on the tumorigenicity of C666-1 in nude mice might due to its inhibition on STAT3 activation when grown in vivo. To mimic the in vivo activation of STAT3 in tumor cells with cytokines secretion from stroma cells in tumor, we used the fibroblast-conditioned supernatant to induce STAT3 activation in NPC cells (Figure 6a and b).