Interferons (IFNs) are cytokines with antiviral, antiproliferative, and immunomodulatory effects. They are crucial in the body's defense against viral infections and in immunosurveillance for malignant cells. IFNs are divided into two main classes: type I IFNs (including IFN-α, IFN-β, IFN-ε, IFN-κ, and IFN-ω) and type II IFN (IFN-γ). Type I IFNs bind a common receptor, while type II IFN binds a distinct receptor. Recent studies have identified a new class of IFNs, IFN-λ, which bind a different receptor and are not discussed here. The signaling pathways for type I and type II IFNs involve the JAK-STAT pathway. Upon IFN binding, JAK kinases phosphorylate STAT proteins, leading to their dimerization and nuclear translocation, where they bind to DNA elements to initiate gene transcription. Type I IFNs also activate the ISGF3 complex, which binds to ISRE elements in the promoters of IFN-stimulated genes (ISGs). Type II IFNs activate STAT1, leading to the formation of STAT1 homodimers that bind to GAS elements in ISG promoters. In addition to the JAK-STAT pathway, other signaling cascades, such as the MAPK and PI3K pathways, are involved in IFN-mediated signaling. The MAPK pathway, including p38, ERK, and JNK, plays a role in antiviral responses and growth inhibition. The PI3K pathway is involved in regulating cell survival and apoptosis, with AKT as a downstream effector. The PI3K pathway also interacts with the JAK-STAT pathway, influencing STAT1 phosphorylation and transcriptional activity. The study highlights the complexity of IFN signaling, involving multiple pathways that regulate gene expression and cellular responses. Understanding these pathways is crucial for developing therapeutic strategies targeting IFN signaling in diseases such as cancer and viral infections.Interferons (IFNs) are cytokines with antiviral, antiproliferative, and immunomodulatory effects. They are crucial in the body's defense against viral infections and in immunosurveillance for malignant cells. IFNs are divided into two main classes: type I IFNs (including IFN-α, IFN-β, IFN-ε, IFN-κ, and IFN-ω) and type II IFN (IFN-γ). Type I IFNs bind a common receptor, while type II IFN binds a distinct receptor. Recent studies have identified a new class of IFNs, IFN-λ, which bind a different receptor and are not discussed here. The signaling pathways for type I and type II IFNs involve the JAK-STAT pathway. Upon IFN binding, JAK kinases phosphorylate STAT proteins, leading to their dimerization and nuclear translocation, where they bind to DNA elements to initiate gene transcription. Type I IFNs also activate the ISGF3 complex, which binds to ISRE elements in the promoters of IFN-stimulated genes (ISGs). Type II IFNs activate STAT1, leading to the formation of STAT1 homodimers that bind to GAS elements in ISG promoters. In addition to the JAK-STAT pathway, other signaling cascades, such as the MAPK and PI3K pathways, are involved in IFN-mediated signaling. The MAPK pathway, including p38, ERK, and JNK, plays a role in antiviral responses and growth inhibition. The PI3K pathway is involved in regulating cell survival and apoptosis, with AKT as a downstream effector. The PI3K pathway also interacts with the JAK-STAT pathway, influencing STAT1 phosphorylation and transcriptional activity. The study highlights the complexity of IFN signaling, involving multiple pathways that regulate gene expression and cellular responses. Understanding these pathways is crucial for developing therapeutic strategies targeting IFN signaling in diseases such as cancer and viral infections.