Within the tumors of each phase, the number of PCNA positive nuclei was variable from one tumor to another, but notably the highest value in any of the phase 4 tumors (20.3%) was less than the lowest of the phase 1 tumors (24.3%), and the average PCNA value for the phase 1 tumors was more than 3 times that of the average value for the phase 4 tumors (48.6% versus 15.0%). Here, PCNA is linked to neoplasm.