PTBP1 and non-small cell lung carcinoma: If PTBP1 was promoting FL splicing of hTERT, then knockdown PTBP1 would be expected to result in a decrease in telomerase activity due to the decrease in FL splicing of hTERT. We started with transient knockdown of PTBP1 in a panel of non-small cell lung cancer cell lines: H1299, H2882, H920, and HCC1359.