EGFR and small cell lung carcinoma: In addition, whereas both EGFR mutants (MutR1 and MutR2) acted as dominant-negative forms interfering with phosphorylation-dependent activation of EGFR and MAPK (Figure 2D-E), only MutR1 reduced ITGB2 levels suggesting specificity in the role of the phosphorylation of the mutated amino acids during non-canonical, ligand-independent integrin signaling in SCLC.