text: *[http://pid.nci.nih.gov/PID/2006/061114/full/pid.2006.001.shtml An Introduction to the NCI-Nature Pathway Interaction Database]
  *[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0000425 Identification of Key Processes Underlying Cancer Phenotypes Using Biologic Pathway Analysis]