To investigate the effects of circ‐CUX1 on expression of parental gene CUX1, circ‐CUX1 or two independent short hairpin RNAs (shRNAs) targeting junction site of circ‐CUX1 (sh‐circ‐CUX1) were stably transfected into tumor cell lines. The gene discussed is CUX1; the disease is neoplasm.