At a molecular level, although MortaparibPlus abrogated mortalin–p53 interactions in both MCF-7 and T47D cells, it activated the p53 signaling only in MCF-7 cells that showed (i) nuclear enrichment of p53, (ii) reactivation of transcriptional reactivation function of p53 and (iii) the transactivation of p53 downstream target gene (p21WAF1) responsible for tumor suppression functions (cell cycle arrest, cell senescence and apoptosis) of p53. The gene discussed is HSPA9; the disease is neoplasm.