CNIH4 and neoplasm: Moreover, IHC staining of CNIH4 in tumor xenografts showed reduced CNIH4 protein expression in PLC/PRF/5 tumor xenografts with circUCK2(2,3) knockdown (Fig. 5M), and increased CNIH4 staining in SNU398 tumor xenografts with WT but not 149-mut circUCK2(2,3) overexpression (Fig. 5N).