Western blot using USP18 polyclonal antibody (Cat # PAB10241) shows detection of a band ~43 KDa band (arrowhead) believed to be to USP18 in lysates from HeLa nuclear extracts (Lane 1) and whole cell lysates from HeLa (Lane 2), A-431 (Lane 3), Jurkat (Lane 4) and HEK293 (Lane 5). Approximately 18 ug of each lysate was run on a SDS-PAGE and transferred onto nitrocellulose followed by reaction with a 1 : 500 dilution of USP18 polyclonal antibody. Signal was detected using standard techniques. The strong band between the 37 KDa and 50 KDa markers is expected to be USP18. The other bands are probably non-specific.