For example, the Kd of binding of erlotinib to its primary cancer target, EGFR, is ∼1 nM compared with a Kd of binding of 3.1 nM to GAK (SuperNova Life Science 2008, Human Kinome Heat Map, http://www.supernovalifescience.com/HM/HM%2041.pdf and [78]). Here, EGFR is linked to cancer.