Metastatic melanoma cells. Fluorescence light micrograph of skin cancer cells that have spread (metastatized). The ability of cancer cells to move and spread depends on actin-rich core structures such as the podosomes (yellow) shown here in melanoma cells. Cell nuclei (blue), actin (red), and an actin regulator (green) are also shown. Melanomas are invasive cancers, and may spread to other parts of the body (metastasis). If this occurs, the prognosis is poor. If the cancer has not spread, surgical removal may effect a cure. Melanomas are the most dangerous form of skin cancer.