Full-length p53 -- the tumor suppressor we depend upon -- consists of 11 exons, or protein-coding segments (top). Alternative splicing and gene mutation can give rise to truncated p53 proteins that promote rather than suppress cancer. Three truncated p53 proteins are compared below, beneath the rendering of the normal ('WT') full-length protein. p53-psi (p53Ψ) is the result of alternative splicing. R213* is a truncated form of p53 that results from a gene mutation. Like p53-psi, it is truncated after the 6th exon. Sordella and colleagues have discovered that both of these short p53 isoforms are pro-metastatic and rely on the same mechanism: they interact with cellular mitochondria, disturbing mitochondrial function.