The XR Factor is a potent blocker for eliminating endogenous rat IgG. By adding XR Factor to BIOCARE’s Mouse on Rat, Goat Polymer or Rabbit on Rodent polymer detection, endogenous rat IgG will dramatically be reduced or completely eliminated. BIOCARE has also developed Rodent Block R that blocks for nonspecific background staining, and at the same time, reduces endogenous rat IgG. The combination of Rodent Block R and the XR Factor allows primary goat, rabbit and mouse antibodies to be used on rat tissues. It can also be used on an automated staining system.