PTBP1 and small cell lung carcinoma: We first analyzed baseline levels of NOVA1, PTBP1 and PTBP2 in a panel of human tissue culture cell lines consisting of lung epithelial cells (HBEC), non-small cell lung cancer cells (H920, A549, H1299, H2887, H2882, and Calu6), small cell lung cancer (SHP-77 and H82), colon cancer (HCT-116), cervical cancer (HeLa) and transformed embryonic kidney (293T) cells.