Keratinocyte basic medium (KBM) and keratinocyte growth medium (KGM; KBM supplemented with bovine pituitary extract, epinephrine, hydrocortisone, transferrin, insulin, and EGF) were from BioWhittaker (Walkersville, MD). Human recombinant HB-EGF was obtained from R&D Systems (Minneapolis, MN). Antibodies against human EGFR, ERK2 (p42 MAPK), phospho-ERK1/2 (p42/p44), c-Src (Src 2), pY20, and pY99 were from Santa Cruz Biotechnology (Santa Cruz, CA). Antibodies against a major substrate of PI3K—AKT, phospho-AKT, and phospho-Src (Y416)—were obtained from Cell Signaling (Beverly, MA). Rabbit anti-EGFR (Y845) was from Biosource (Camarillo, CA). The EGFR inhibitor tyrphostin AG 1478 was from Sigma-Aldrich (St. Louis, MO). The Src inhibitor PP2 (4-amino-5-(4-chloro-phenyl)-7-(t-butyl) pyrazolo [3,4-d] pyrimidine), the phospholipase C (PLC) inhibitor U73122, and the PI3K inhibitor LY294002 were from Calbiochem (La Jolla, CA). Boyden chamber and polycarbonate membranes (14-μm pores) were purchased from Neuroprobe (Cabin John, MD) and Osmonics, Inc. (Livermore, CA), respectively. Fibronectin collagen coating mix (FNC) was from Biological Research Faculty & Facility (Ljamsville, MD). All other chemicals were purchased from Sigma-Aldrich.