ERBB2 and cholangiocarcinoma: EGF-mediated PTK6 activation promotes the proliferation of CC cells through the formation of PTK6/EGFR and PTK6/ERBB2 complexes, which in turn activate Src associated in mitosis of 68 kDa (SAM68); high levels of both PTK6 and EGFR expression are closely correlated with the upregulation of Ki67 as a prognostic marker of cancer [32].