DLL3 and small cell lung carcinoma: Moreover, SCLC cells develop resistance to agents that target DLL3 by reverting to a non-DLL3-expressing phenotype or using alternative signaling pathways, such as the Notch, Wnt/β-catenin, MAPK/ERK, and PI3K/AKT pathways, which ensure tumor cell survival and proliferation in the absence of DLL3 [56].