Epitope Tag Positive Control Lysates. Multiple Tag Cell Lysate is whole E. coli cell lysate comprised of about 30% specially designed fusion protein, which act as a positive control for Western blot or Dot blot. The fusion protein is a 52 kD protein containing 16 commonly used tags, which are, in order, Trx, T7, HSV, C-Myc, SVS-g, Glu-Glu, V5, E tag, DYKDDDDK, S-tag, HA, KT3, E2, AU1, AU5, and His tag.