We describe a method of regulating expression of a nucleic acid sequence in a primary cell, the method comprising providing a nucleic acid binding polypeptide capable of binding to the nucleic acid sequence, and contacting the nucleic acid binding polypeptide with the nucleic acid sequence in the primary cell to regulate its expression. Nucleic acid binding polypeptides capable of binding to and regulating the expression of a nucleic acid sequence in a primary cell is also disclosed.
