The Control ∆E1 Left Arm (Sfi) is a 431 bp-long PacI-DraIII DNA fragment isolated from pZAP1.1. It contains the left ITR, packaging signal and the multiple cloning site. This DNA fragment can be used to control the efficiency of the ligation with RightZAP1.1 and RightZAP1.2. By transfecting the ligation mixture into helper cells (e.g. 293 cells), you will be able to construct an E1-deleted adenovirus without expression cassette, which will be useful as negative control in your future experiments. Enough material is provided to perform this control ligation twice.