Figure 2

Resistance to CCI-779 is associated with high EGFR expression but does not correlate with reduced activity of CCI-779 in blocking mTOR-signaling. (A) Two resistant (red, UT-SCC-23 and UM-SCC-11B) and two sensitive (green, UT-SCC-15 and UM-SCC-25) cell lines were treated with 100 ng/ml CCI-779 for 24 h. The activation of the MAPK- (p-Erk) and mTOR- (p-S6) signaling pathways, as well as the expression of the housekeeper protein GAPDH were evaluated using Western Blot. (B) All 10 cell lines were analyzed regarding their basal expression levels of EGFR, p-Erk/Erk (MAPK pathway), and p-S6K/S6K (mTOR pathway) by Western Blot.