In Phase 1 of this study, the purpose is to evaluate the safety, tolerability, and highest safe dose of the multiple receptor tyrosine kinase inhibitor (including VEGFR2, MET, and RET) XL184 in combination with the EGFR inhibitor erlotinib administered to adults with Non-Small-Cell Lung Cancer (NSCLC). In Phase 2 of this study, the purpose is to evaluate the objective response rate of daily oral administration of XL184 with or without erlotinib in subjects with NSCLC who have progressed after responding to treatment with erlotinib.