HIF1A and neoplasm: Furthermore, analysis of protein extracts of the tumor tissues from mice inoculated with MDA-MB-231 cells with IDH2-knockdown showed that the protein level of HIF1α and its target genes LDHA and ALDOA were substantially decreased (Fig. 4c, d), indicating that IDH2 had a significant impact on HIF1a and its downstream molecules in vitro and in vivo.