STAT3 and neoplasm: Consistent with the finding that activation of CSF1R induces STAT3 phosphorylation (p-STAT3) in CRC cell lines 21, the frequency of cells displaying STAT3 activation was decreased in adenomas of Csf1rΔIEC;ApcMin/+ mice, whereas deletion of Mir34a increased the number of p-STAT3-positive tumor cells (Fig. 3E).