The protein classes show a summary of genes identified in various protein classifications. Each row shows the total number of genes for a particular protein class as well as the number of those genes with experimental data in HPA for the corresponding proteins based on antibody-based profiling. All protein classes have been categorized into three different tables: "Function and compartment based", "Disease and drug related", and "Evidence based". Clicking one of the numbers in the tables retrieves a search result with the selection of genes belonging to the class, along with additional data. For each class, where applicable, there is also a link to the original source of the gene list. A number of classes contain a selection of subclasses which unfolds when the parent class (shown in bold and with arrows) is clicked. Some subclasses (marked with an asterisk) are not included in the total number of genes for the parent class.