A process of producing one or more than one protein of interest, comprising: (a) providing a plant or plant cells comprising a first heterologous nucleotide sequence comprising a nucleotide sequence encoding an RNA replicon, and a first inducible promoter operably linked to said nucleotide sequence encoding said RNA replicon; said RNA replicon not encoding a protein providing for cell-to-cell movement of said RNA replicon in said plant; said RNA replicon encoding a polymerase and said one or more than one protein of interest, said polymerase being adapted for replicating said RNA replicon; and (b) inducing, in said plant or plant cells of step (a), said inducible promoter, thereby producing said one or more than one protein of interest in said plant or plant cells.