IDH1 and neoplasm: To provide further evidence for the selection against IDH1R132H expression in tumor growth, we observed 76% reduction of YFP–IDH1R132H transcript levels accompanied by 35% reduction of PDGFB transcript levels compared with those in YFP–IDH1 tumors (Figure 2A, 2B), a finding in agreement with the selection against IDH1R132H transgene in neurosphere culture [15].