In the course of their investigations into cancer cell growth, a team of pharmaceutical researchers has discovered a critical oncoprotein (a protein that promotes cancer cell growth).

Now they have developed a new drug that binds to a single site on the oncoprotein with an equilibrium dissociation constant (K_d) of 200 pM.

What concentration of the drug would they need to mix with the oncoprotein so that 90% of the oncoprotein molecules will be bound to the drug?