In contrast, a passive mechanism has been suggested in work by others on CT26 murine colon carcinoma tumors in BALB/c mice, where an increase of TNF-α in the blood after intravenous administration of a hisG aroA double mutant of S. Typhimurium promoted a blood influx and therefore, bacteria were able to reach this tissue in a passive mechanism [70]. This evidence concerns the gene TNF and colon carcinoma.