Having verified that both the linear and cyclizedcycRGD-mCh-P16p could enter cells, we proceeded to investigate theability of these proteins in halting cell cycle progression, and moreimportantly whether cyclization of the P16p could indeed endow cycRGD-mCh-cycP16pwith enhanced cell cycle arrest ability, and in turn a more potentinhibitory effect on cancer cell growth. This evidence concerns the gene PMCH and cancer.