IDH1 and glioblastoma: In contrast, secondary glioblastoma more often shows tumor protein p53 (TP53) mutations, and fairly consistently exhibits the genetic mutation of isocitrate dehydrogenase 1 (IDH1), a negative regulator of hypoxia-inducible factor 1-alpha (HIFA), whereas IDH1 mutations are barely detectable in primary glioblastoma [1].