Figure 1. Principle of the Tet-on inducible gene expression system regulating tyrosinase (TYR) gene expression using Dox.

The TYR reporter gene is inserted into cells through the method of gene transfer. Gene expression product tyrosinase, the key enzyme, catalyses the process in melanin production. Melanin then serves as a multifunctional target for photoacoustic imaging (PAI), positron emission tomography (PET) and magnetic resonance imaging (MRI) multimodal imaging.