While the role ATO in SCLC is less reported, APA (TKI) was found to retard the growth of SCLC cells by downregulating the expression of VEGF, P-VEGFR2, P-PI3K, P‐Akt, P‐ERK1/2, Ki‐67 and CD31 [13]. This evidence concerns the gene KDR and small cell lung carcinoma.