BÜHLMANN’s Kinase Inhibition Assay Testing Potency and Efficacy of Inhibitors of PI3K δ, PI3K γ, BTK and SYK Activity Biomarker assays are developed specifically for pharmacokinetic and pharmacodyamic (PK/PD) models during drug discovery and are often used to test efficacy and toxicity. Inhibitors of PI3K, BTK and SYKpathways are a large focus for pharmaceutical companies