Notably, we showed that depletion of EGR4 by siRNA led to a significant reduction in cell proliferation in SBC-5, SBC-3 and NCI-H1048 cells, and that EGR4 transactivated a set of genes possibly related to lung cancer cell growth including four EGR4-downstream genes, DLX5, RAB15, SAMD5 and SYNPO. Knockdown of the expression of these genes by siRNA led to a significant reduction in cell growth in SCLC cells, suggesting that these genes are involved in the growth of SCLC lung cancer cells. This evidence concerns the gene RAB15 and lung cancer.