PCNA and glioblastoma: When examining if ATX-101 affected PCNA expression and/or its nuclear distribution in four GBM cell lines and one GIC cell line, it was found that ATX-101 dose dependently inhibited the expression of total PCNA protein at doses below IC50 values in all the cell lines examined (Figure 2A,B; U251 (IC50 = 4.9), U87MG (IC50 = 4.3), GSCs-5 (IC50 = 4.9), A172 (IC50 = 6.4), and T98G (IC50 = 7.1)).