The classic study by Folpe et al., using the clone 8G7G3/1 (Agilent/Dako), showed that TTF-1 was positive in 20 of 21 SCLCs [5]. A study by Misch et al. using the SP141 TTF-1 clone (Ventana Systems) found 38 of 221 SCLC patients had TTF-1-negative tumors and that the TTF-1 status did not predict survival [3]. The gene discussed is TTF1; the disease is small cell lung carcinoma.