Cyclin-dependent kinase that acts as a master regulator of the mitotic and meiotic cell cycles. May drive the G1-S transition. Plays a role in mitotic exit. Plays a role in the expression of morphology-related transcription factors, and especially hyphae-specific genes. Binds distinct cyclin subunits as cells progress through the division cycle or flamentous growth. The CDC28-CLB2 complex regulates cytokinesis partly by phosphorylating the actomyosin ring component IQG1. The CDC28-CLN3 complex phosphorylates SLA1 which regulates cortical actin patch dynamics. The CDC28-CCN1 complex phosphorylates CDC11 and SEC2 upon induction of filamentous growth. The CDC28-HGC1 complex also phosphorylates SEC2 and maintains CDC11 phosphorylation throughout hyphal growth. Moreover, the CDC28-HGC1 complex phosphorylates and prevents RGA2 from localizing to hyphal tips, leading to localized CDC42 activation for hyphal extension. CDC28-HGC1 phosphorylation of EFG1 represses cell separation genes during hyphal growth. Additional substrates for CDC28 are RFA2 in G1-phase; MOB2, which is required for the maintenance of polarisome components and for inhibition of cell separation in hyphae; and GIN4 to regulate its association to SEP7 and subsequent septin ring assembly