PROJECT SUMMARY Protein phosphorylation can activate, inhibit, or modify protein’s function. Small molecules that block protein phosphorylation via kinase inhibition exist, but methods to induce phosphorylation of any protein on demand do not exist. We propose to develop a new class of small molecules, termed PHosphorylation Inducing Chimeric Small molecules (PHICS), which will induce protein phosphorylation with dose and temporal control. PHICS will be formed by joining a small-molecule kinase binder with a small-molecule binder of the target protein so that an active kinase is brought into proximity to the target protein to initiate phosphorylation. 1