Abstract: New synthetic expression cassettes comprising a minimal promoter and a cell-specific enhancer for expression of a nucleic acid of interest in one or more specific cell subtypes are disclosed. Vectors and host cells comprising such synthetic expression cassettes are also disclosed. The application also discloses methods for expressing a nucleic acid of interest, such as a nucleic acid encoding a chimeric antigen receptor (CAR), in a cell and for treating diseases or conditions such as cancers and genetic diseases using the synthetic expression cassettes, vectors and cells.