MLH1 and leukemia: DHX38 restricts chemoresistance by regulating RELL2 intron retention in pancreatic ductal adenocarcinoma.[30] The retention of intron 2 in CD19 confers to CART‐19 resistance in leukemia.[31] In our study, LUC7L2 was found to mediate MLH1 intron 7 retention, and PTCs in intron 7 were recognized by NMD and led to MLH1 mRNA degradation and thus, suppression of MLH1 expression.