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. Here, SYNPO is linked to lung cancer.