The present invention provides a method of inhibiting cancer cell proliferation by suppressing a function of ZNF143, a cancer cell proliferation inhibitor containing as an active ingredient a substance capable of inhibiting a function of ZNF143, like a ZNF143-specific siRNA, a prophylactic and/or therapeutic drug for cancer, a method of detecting cancer cells, a diagnostic reagent for cancer, a vector and transformant cell incorporating the vector, and a screening method for a substance possessing cancer cell proliferation inhibitory activity with the amount of inhibition of the binding of ZNF143 protein as an index.
