CD155, also known as the poliovirus receptor (PVR) or Nectin-like molecule 5 (Necl5), has been identified as an unfavourable prognosis marker and has an overexpression in a number of cancers, including glioblastoma multiforme [9], non-small-cell lung carcinoma [10], pancreatic cancer [11], melanoma [12], hepatocellular carcinoma [7], colorectal cancer [13], and sarcoma [14, 15]. Here, PVR is linked to cancer.