Identification, quantification, and evolutionary analysis of a novel isoform of MCM9

► Identified a novel alternatively spliced variant of MCM9M ► Expression of both MCM9 isoforms varies across a panel of cancer cell lines. ► MCM9 expression is cell-cycle regulated and induced in S-phase. ► MCM9L expression is specifically induced after exposure to Mitomycin C. ► The C-terminal extension of MCM9L is a recent evolutionary addition.