NIFK (Nucleolar protein interacting with the FHA domain of pKi-67) or MKI67 FHA domain-interacting nucleolar phosphoprotein is a 34 kDa protein localized within nucleolus of cell. NIFK has a potential RNA-binding domain which interacts with the forkhead-associated domain of the MKI67. NIFK plays a role in mitosis and cell cycle progression. Sequential phosphorylation on Thr-238, Thr-234 and Ser-230 enhances MKI67 binding. NIFK is highly expressed in brain and kidney tissues.