PTK6-mediated phosphorylation activates STAT3 transcription factor via STAP2 adapter protein. STAT3 transcriptional target SOCS3 is a negative regulator of PTK6 and inhibits PTK6-mediated phosphorylation of STAT3, thus creating a negative feedback loop (Liu et al. 2006, Ikeda et al. 2009, Ikeda et al. 2010). PTK6 may also activate STAT5-mediated transcription (Ikeda et al. 2011).