Signal transducer and activator of transcription 3 contributes to cancer cell survival, proliferation and malignant transformation even in conditions where it is not stimulated by cytokines,25, 29, 30, 31, 32 and mitochondrial STAT3 could promote oncogenic transformation in certain biological contexts.13, 33 In order to know if there were biological consequences of the observed changes of behavior in unstimulated STAT3 dimers, HeLa cells were transfected with the different combinations of constructs and their proliferation was determined 24 hours later (Figure 3). The gene discussed is STAT3; the disease is cancer.