Please refer to the "Sensitivity/Specificity" section of the antibody webpage. Sensitivity to transfection or recombinant protein antibodies alone is insufficient to detect endogenous levels of the target. Endogenous sensitive antibodies are applicable to all sample types (endogenous, transfected, or recombinant proteins). Additionally, it may be necessary to increase or decrease the amount of antibodies used to obtain the optimal signal, depending on the abundance of target proteins in the sample. We suggest using the dilution ratio displayed on the product website and manual as the starting point for optimization. 

Another factor to consider is the species reactivity of antibodies. CST has conducted internal validation on the species listed in the "Reactivity" section of the product webpage. If your target species are not listed, please contact our technical support team, who will be happy to help you determine the expected reactivity of the antibody with the protein sequence of your model species.