Internal reference is internal control. For mammalian cell expression, it generally refers to housekeeping proteins encoded and expressed by housekeeper genes. Their expression in various tissues and cells is relatively constant. It is often used as a reference when detecting changes in protein expression levels. In the Western Blotting experiment, in addition to protein extraction, protein quantification, sample loading electrophoresis, membrane transfer, target protein antibody incubation, color development and other steps, internal reference detection is also required to correct the experimental errors in protein quantification and sample loading and ensure the accuracy of experimental results. To detect whether the expression product of a gene is correct, or to compare the relative changes in the amount of expression product, the preferred method is Western Blot. The use of internal reference in Western Blotting is actually another way of using the antibody corresponding to the internal reference to detect the internal reference in the WB process, so that the expression of the internal reference can be detected while detecting the target product. Since the expression of the internal reference in various tissues and cells is relatively constant, the amount of internal reference in each sample can be used to correct the loading error, so that the semi quantitative results are more reliable. In addition, the internal reference can be used as a blank control to detect whether the protein transmembrane is complete, whether the whole Western Blot color or luminescence system is normal.