Despite the important role of MAPKs in signal transduction, their functions in the cellulase hyper-producing filamentous fungus Tmk3. In thiswork,we constructed and explored the features ofH. jecorina Dtmk2 to identify the role of this Slt2-homologous Tmk2. It is suggested from the results that Tmk2 is involved in cell wall integrity, sporulation and cellulase production. Although bearing similar roles in cell wall integrity maintenance, Tmk2 and Tmk3 appear to also have distinct functions: Tmk3 participates in high osmolarity resistance while Tmk2 does not; Tmk2 participates in sporulation but not Tmk3; Tmk3 is involved in promoting cellulase productionwhileTmk2 is involved in repressing cellulaseformation. These studies provide the first insight into the function of Tmk2 in H. jecorina and contribute to understanding the signal transduction processes leading to the regulation of cellulase production in this important cellulase hyper-producer. Published Hypocrea jecorina haven’t been studied except for the Hog1-like