However, there was no differentiation in tumor cell growth inhibition between a potent PTK6 kinase inhibitor and a PTK6-negative control compound, nor a correlation between the sensitivity of tumor cells to PTK6 inhibitors and the PTK6 expression or activation levels, therefore arguing against an oncogenic role of PTK6 kinase activity in tumor cells suggested by other reports (16, 19). The gene discussed is PTK6; the disease is neoplasm.