The idea that the gap junction family of proteins, connexins, are tumour suppressors has been widely supported through numerous cancer models. However, the paradigm that connexins and enhanced gap junctional intercellular communication is of universal benefit by restricting tumour growth has been challenged by more recent evidence that suggests a role for connexins in facilitating tumour progression and metastasis. Therefore, connexins might be better classified as conditional tumour suppressors that modulate cell proliferation, as well as adhesion and migration.