Task: Named Entity Recognition
Input (English):  The promoters of the adenovirus 2 major late gene , the mouse beta - globin gene , the mouse immunoglobulin VH gene and the LTR of the human T - lymphotropic retrovirus type I were tested for their transcription activities in cell - free extracts of four cell lines ; HeLa , CESS ( Epstein - Barr virus - transformed human B cell line ) , MT - 1 ( HTLV - I - infected human T cell line without viral protein synthesis ) , and MT - 2 ( HTLV - I - infected human T cell line producing viral proteins ) .
Output (English): viral proteins