PMS2,also named as PMSL2,belongs to the DNA mismatch repair mutL/hexB family. It is a component of the post-replicative DNA mismatch repair system (MMR). It heterodimerizes with MLH1 to form MutL alpha. MulL alpha (MLH1-PMS2) interacts physically with the clamp loader subunits of DNA polymerase III,suggesting that it may play a role to recruit the DNA polymerase III to the site of the MMR. It also implicated in DNA damage signaling,a process which induces cell cycle arrest and can lead to apoptosis in case of major DNA damages. Defects in PMS2 are the cause of hereditary non-polyposis colorectal cancer type 4 (HNPCC4). Defects in PMS2 are a cause of mismatch repair cancer syndrome (MMRCS).