First, the most important limitation in our eyes is that although Papyrus consists of nearly 60 million activity data points, the data it contains is extremely sparse as only 0.67% of the activity data matrix is represented by the 1.25 million compounds and almost 7,000 proteins. This is unfortunately hard to avoid as many of the compounds have simply not been tested on all proteins. Only relatively popular proteins will appear in the data that is aggregated here. This makes it hard to model proteins that are understudied, however if data are available they can be added to the Papyrus dataset to create a more comprehensive set.