Abstract: The present invention relates to a polynucleotide comprising a gene encoding a hook protein and a gene encoding a protein of interest, said protein of interest being either a secretory protein or a cell membrane-anchored protein, wherein: said gene encoding the hook protein is under the control of a first transcription-activating signal, said gene encoding the protein of interest is under the control of a second transcription-activating signal, said second transcription-activating signal allowing a lower rate or frequency of transcription initiation than the first transcription-activating signal, said hook protein is fused to a cellular compartment-retention peptide, and said protein of interest is fused to a hook protein-binding domain It also related to vectors comprising the polynucleotide, cells comprising the polynucleotide or the vector and compositions comprising the same.

Abstract: The present application relates to fully humanized anti-FGFR4 single domain antibodies (sdAbs) and variants thereof. The present invention further relates to functionalized drug nanocarriers, nucleic acids, vectors, host cells, immune cells comprising said sdAbs, and compositions comprising thereof, as well as their use for therapy.