An immunocapture-based in vitro kinase assay on an integrated polydimethylsiloxane (PDMS) microfluidics platform that can reproducibly measure kinase activity from as few as 3,000 cells is described. For this platform, the standard radiometric 32P-ATP labeled phosphate transfer assay was adopted. Implementation on a microfluidic device required the development of methods for repeated trapping and mixing of solid-phase affinity micro beads. A solid state beta-particle camera imbedded directly below the microfluidic device was used to provide real-time quantitative detection of the signal from this and other microfluidic radio bioassays. The integrated device can measure ABL protein kinase activity from BCR-ABL positive leukemia patient samples, and can measure the small molecule phosphorylation such as phosphorylation of the deoxycytidine analog 18F-FAC by deoxycytidine kinase (dCK) isolated from cell lysates.