STAT3 and colorectal carcinoma: Furthermore, it has been shown in CRC cell lines that signal transducer and activator of transcription 3 (STAT3) is a negative regulator of MICA transcription and that the upregulation of MICA ligand on tumor cells correlates with dephosphorylation of STAT3 (Bedel et al., 2011; López-Soto et al., 2013).