Jeremy, I have been trying to follow the steps in filtering Cufflink out put files you have described in one of the previous messages ( http://gmod.827538.n3.nabble.com/Re-downstream-analysis-of-cuffdiff-out-put-... ): I have shared histroy with you, but in summary: File 35: when Filter GTF data by attributes value list on data 11 (combined GTF) and data 33 (which is gene expr file) . Will not this should have one gene per row. But it is not? File 39: Filter GTF file by attribute value list on data 11 and data 38 (Cuffdiff splicing expr) it failed. I would assume that it should filter on the basis of TSSid . The error message is Traceback (most recent call last): File "/var/opt/galaxy/g2test/galaxy_test/tools/filters/gff/gtf_filter_by_attribute_values_list.py", line 67, in filter( gff_file, attribute_name, ids_file, output_file ) File "/var/opt/galaxy/g2test/galaxy_test/tools/filters/gff/gtf_filter_by_attribute_values_list.py", line 57, in filter if attributes[ attribute_name ] in ids_dict: KeyError: 'tss_id' 40 : Filter GTF data by attribute list on data 11 and 34 (tss group exp) failed and error message is: Traceback (most recent call last): File "/var/opt/galaxy/g2test/galaxy_test/tools/filters/gff/gtf_filter_by_attribute_values_list.py", line 67, in filter( gff_file, attribute_name, ids_file, output_file ) File "/var/opt/galaxy/g2test/galaxy_test/tools/filters/gff/gtf_filter_by_attribute_values_list.py", line 57, in filter if attributes[ attribute_name ] in ids_dict: KeyError: 'tss_id' I would consider that if one gene has different Id than there is splicing . However in contrast isoform file with transcript Id is working fine (File 20) On a different note can I convert GTF file to txt tab delaminated file I tried to convert file 11 in txt (following Edit attributes) but the file is not properly formatted especially col-pid and TSS id. Am I doing something wrong. Thanks.