following HindIII digestion. Due to the use of the HindIII site in the pGL4.21 vector, the −391 to +247 fragment was only subcloned in the reverse orientation, and despite several attempts, no colonies were obtained with this fragment in the forward orientation. The −109 to +247 and the −53 to +247 fragment were generated using PCR and cloned into the pGL4.21 vector using XhoI and SstI digestions.
