Therapies targeted at the extracellular importin α1 (both the released form and the cell surface-localized form), as well as those that are targeted at released importin α1-mediated induction of FGF1 signalling, are expected to perturb the proliferation of importin α1-releasing cancer cells, thereby providing a novel option for the treatment of cell surface importin α1-related cancers. Here, FGF1 is linked to cancer.