Under these conditions, we exposed U-87 MG and TS#163 GBM cells, either siRNA-control or PKM2-silenced, to CPZ and assessed gene expression of CCND1, cMYC, and also the STAT3 downstream gene MEK5. While, in GBM cells, CPZ downregulated the expression of these genes in siRNA control cells, the effect of the drug was significantly lower or missing in siRNA-PKM2 cells. The gene discussed is CCND1; the disease is glioblastoma.