The epidermal growth factor receptor (EGFR; ErbB-1; HER1) is the cellsurface receptor for members of the epidermal growth factor family. Overexpression and/or hyperactivation of EGFR kinase is associated with several human cancers such as lung, glioblastoma, and epithelian tumors of the neck and head, leading to the development of anticancer therapeutics targeting EGFR. EGFR(L858R) mutation is found in ~40% of EGFR-mutated lung tumors. The EGFR(L858R) Kinase Assay Kit is designed to measure EGFR (L858R) Kinase activity for screening and profiling applications using Kinase-Glo® MAX as a detection reagent.