• Staurosporine is a highly potent, ATP-competitive, and broad-spectrum protein kinase inhibitor. It exhibits inhibitory activity with IC₅₀ values of 6 nM for PKC, 15 nM for PKA, 2 nM for c-Fgr, and 3 nM for phosphorylase kinase. Additionally, it inhibits TAOK2 with an IC₅₀ of 3 μM. Staurosporine is well-known for its role in inducing apoptosis.