STAT3 and cancer: We then determined the activation status of downstream FGFR cancer-related signaling pathways (specifically, the STAT3, AKT and MAPK pathways) in these cell lines; Generally, FGFR4-388Arg overexpression increased pSTAT3 and p-42/p44 levels compared to their respective empty vector control and FGFR4-388Gly overexpressing cell lines.