STAT3 and laryngeal carcinoma: Notably, phosphorylated STAT3 and its target genes, including Mcl-1 and cyclin D1, were augmented in RR-HEp-2 cells compared to the control cells, whereas p53, a protein that is negatively regulated by STAT3 [27], was downregulated (Fig. 3A), indicating that STAT3 activity is increased in radioresistant laryngeal cancer cells.