Gene expression patterns for SUM102 cells treated with gefitinib or cetuximab. Unsupervised hierarchical cluster analysis was performed on 48 h inhibitor treated and 4 h, 8 h, and 24 h post 48 hr inhibitor treated samples. A) The complete cluster overview with the colored bars indicating the location of the clusters shown in C-G. B) Close up of the experimental sample associated dendrogram. C+D) 4 h and 8 h post treatment induced genes including the EGFR ligands Amphiregulin and Epiregulin. E) Genes involved with the G1/S phase transition induced beginning in the 4 h post inhibitor and continuing though 24 h. F) Genes involved in DNA synthesis induced at 8 h post inhibitor and continuing through 24 h. G) Proliferation genes typically observed in tumor derived profiles including STK6 and Cyclin B1.