ESR1 and cancer: A different view is given by the analysis of the third gene set, TRANSMEMBRANE_RECEPTOR_PROTEIN_KINASE_ACTIVITY, which only contains genes encoding the RTKs: besides the activation of the cancer-related functions and EGF, other upstream regulator (FGF2 and HGF, and EPAS1, ESR, KLF4 and MYC, growth and transcription factors, respectively) were predicted to be activated in the MM OC subgroup (Table 4).