Estrogen level is an important indicator for breast cancer and plays a critical role in breast cancer progression. The binding information of ER can provide valuable information for new therapy development. The names of the compounds are downloaded from Tong et al . Pipeline pilot [35] is used to retrieve chemical structures from PubChem (Figure ). The authors developed decision forest to predicate whether a compound is an ER receptor or not and tested on the dataset by using 10 and 88 descriptors. The final prediction accuracy is 0.927 and 0.978 (error rate) respectively. for CNS drug development. Like the Estrogen receptor dataset, only the names of the compounds are available from Kortagere et al . The same application and protocol (Figure ) are used to retrieve chemical structures from PubChem. Kortagere utilized SVM to predicate BBB penetration; the final accuracy for the prediction is from 0.8 to 0.84 (error rate).