We examined whether histamine could regulate cell proliferation and expression of the early response gene c-fos in HEK-293 cells stably transfected with the human H₂ receptor (HEK-H₂). Histamine stimulated [³H]thymidine incorporation [50% effective concentration (EC₅₀) = 3.6 × 10⁶ M] in HEK-H₂ cells in a cimetidine-sensitive manner and increased c-fos mRNA in a time-dependent fashion, reaching maximal induction after 30 min. Histamine induced luciferase activity in HEK-H₂ cells transiently transfected with a construct containing the luciferase reporter gene (Luc) coupled to the serum response element (SRE) of the c-fos gene promoter (EC₅₀ = 1.5 × 10⁶ M) or a plasmid containing the SRE core fragment (bases 320 to 298). The protein kinase C (PKC) inhibitor staurosporine and long-term pretreatment of HEK cells with phorbol ester inhibited the effect of histamine on PKC activation, SRE-Luc activity, and [³H]thymidine incorporation. We have demonstrated that activation of the human H₂ receptor can lead to induction of c-fos gene transcription and cell proliferation through a PKC-dependent mechanism.