UASt regulatory sequences drive expression of a fusion protein composed of the destabilized VHH(dGBP1) nanobody, a Tag:HA tag and a truncated form of Src42A (amino acids 214-517, spanning the ATP-binding site and kinase domain). The Src42A sequence contains two amino acid substitutions: a Y511F mutation in a crucial regulatory residue, and a K276M mutation that abolishes catalytic activity.