Nevertheless, the overall expression of wild-type PTGFRN, NOTCH2 and its targets (PTCRA, HES1, HES5) are less affected in cancer (Table S6), indicating that 1) the PTGFRN-NOTCH2 fusion could occur in a subset of cancer cells or 2) that the fusion is heterozygous in cancer tissue and the fusion allele might be expressed at an extremely lower level. This evidence concerns the gene HES1 and cancer.