Updated publication reference for PubMed record(s): 31194741. The septation initiation network (SIN), composed of a conserved SepH (Cdc7p) kinase cascade, plays an essential role in fungal cytokinesis/septation and conidiation for asexual reproduction, while the mitogen-activated protein kinase (MAPK) pathway depends on successive signaling cascade phosphorylation to sense and respond to stress and environmental factors. In this study, a SepH suppressor–PomA in the filamentous fungus A. nidulans was identified as a negative regulator of septation and conidiation such that the pomA mutant was able to cure defects of sepH in septation and conidiation and overexpression of pomA remarkably suppressed septation. Under the normal cultural condition, SepH positively regulates the phosphorylation of MAPK-HogA, while PomA reversely affects this process and the phosphorylated HogA in MAPK could be a downstream product of the activated SIN. However, under the osmostress condition, the induced phosphorylated HogA is capable of bypassing the requirement of SepH to fulfill septation and conidiation. Findings demonstrate that crosstalk exists between the SIN and MAPK pathways.