Originally isolated in 1977 by Satoshi Ōmura and colleagues from the bacterium Streptomyces staurosporeus (with its absolute structure solved by X-ray crystallography in 1994), staurosporine was the founding member of the bis-indole indolocarbazole alkaloid family.
Its rigid planar indolocarbazole ring system mimics the adenine ring of ATP and forms hydrogen bonds with the kinase hinge region, inhibiting hundreds of human protein kinases at nanomolar concentrations.
Because its extreme promiscuity across the kinome precludes systemic clinical use (though cleaner derivatives such as midostaurin are approved drugs), staurosporine is universally used in cell biology as a rapid positive control to induce intrinsic mitochondrial apoptosis.