MSH2 and non-small cell lung carcinoma: Reduced expression of MLH1 in NSCLC has been reported at frequencies of 20–61%,5,18 and in some studies has been associated with microsatellite instability.5,18 Decreased MSH2 expression has been reported at similar rates ranging from 18%4 to 58%,16 and in our study population altered MSH2 was less frequent than MLH1.