PTK2 and small cell lung carcinoma: FAK splicing variants were selected for further investigation because these variants are observed at relatively low frequencies in NSCLCs but are not reported in SCLCs.55 Moreover, FAK inhibitors have exhibited inhibitory effects on SCLC cells57 and induced stable disease in 1/1 patients who received PF562271 in a phase I trial.58 In SCLC, two additional spliced boxes of 18 bp (Box 6) and 21 bp (Box 7) were included on either side of the codon encoding autophosphorylation site Y397, designated FAK6, FAK7, and FAK6,7, respectively (Fig. 5b and Supplementary Fig. 10a).