APOL4 and central nervous system cancer: Additionally, the protein level of APOL4 in gliomas was evaluated by the HPA database, and the IHC staining of APOL4 is shown in Figure 1D. The location of the APOL4 protein in the SH-SY5Y cell line (human neuroblastoma cell) was assessed, and the results indicated that APOL4 was located in the intracellular membrane (Figure 1E).