PCNA and neoplasm: The inhibitory effect of honokiol on tumor xenograft growth was associated with the: (i) inhibition of PCNA, and correction of dysregulated proteins of cell cycle regulation, (ii) induction of apoptotic cell death of tumor cells, as indicated by the increased levels of activated caspase-3, and (iii) reduction in the levels of EGFR, pAkt and mTOR, including downstream targets of mTOR signaling in tumor xenograft samples collected at the termination of the in vivo animal experiments.