Constitutive Stat3 activation seems to be one of the critical pathways in CRC and is considered to have an important role in CRC carcinogenesis.19, 20, 21, 22 Moreover, Stat3 phosphorylation at tyrosine residue 705 (Y705, p-Stat3) has high expression in human colon cancer cell lines.11 To investigate whether nifuroxozide has direct effects on CRC tumor cells, we tested the proliferation inhibition caused by nifuroxazide in HCT116 and HT29 human CRC cell lines, as well as murine CT26 tumor cells by the MTT (3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide) assay. Here, STAT3 is linked to malignant colon neoplasm.