Standardization of protein position in silver‐stained two‐dimensional polyacrylamide gel electrophoresis

Methods for standardization of silver‐“stained” protein position in two‐dimensional polyacrylamide gel electrophoresis are presented for their application to simultaneous multiple gel systems. Four methods are discussed: the use of a single gel per simultaneous run for standardization with either (1) known quantities of commercially prepared high‐or low‐molecular‐weight standards or (2) a known biological preparation such as T4 phage coat proteins; the use of each gel per simultaneous run to standardize itself by (3) including an internal carbamylation train such as creatine phosphokinase and using a one‐dimensional gel pattern of proteins such as rat heart whole homogenate along the margin(s) or (4) identifying “marker” protein spots in test samples that occur in all gels in a given study and standardizing to relative position. Method four is discussed in detail and examples given of its use in a comparative study of proteins in spontaneous primary hepatocellular carcinomas occurring in mice, and its use compared to the other methods.