​Interferons α, β and γ are cytokines produced and secreted by animal cells after infection by viruses. Which one of the following statements about interferons is INCORRECT?​

Correct option is C

Explanation-

Interferons (IFNs) are cytokines produced by animal cells in response to viral infections. They help regulate the immune response by activating signaling pathways that lead to the expression of antiviral and immune-modulating genes.
Option  a  -  When mammalian cells are incubated with interferons, activation of STATs links stimulation of cell surface receptors with gene expression.
Interferons bind to their receptors → activate JAK-STAT pathway. STAT proteins (Signal Transducers and Activators of Transcription) are phosphorylated, dimerize, and move into the nucleus to promote gene expression.
This is a correct statement.
Option  b  - Increase in the expression of genes after addition of IFNα results only after activation of the ISRE.
IFN-α and IFN-β induce genes through the Interferon-Stimulated Response Element (ISRE). These genes are part of the antiviral state induced by Type I interferons.
This is a correct statement.
Option c  - The receptors of all three interferons belong to the Ig superfamily of receptors and do not lead to downstream phosphorylation events.
Interferon receptors do NOT belong to the Ig superfamily. They are type II cytokine receptors (not Ig-like). They do lead to downstream phosphorylation, especially via JAK-STAT signaling.
So this statement is incorrect on two points:
                                              1.   Wrong receptor classification
                                              2.    Incorrectly claims no phosphorylation
Option d  - An important feature of interferon-STAT signaling pathway is its specificity: each type of interferon induces transcription of a unique subset of genes.
Type I IFNs (α, β) vs Type II IFNs (γ) signal through different receptor complexes, activating different STATs (e.g., STAT1, STAT2). This results in specific gene expression patterns based on the interferon type.
This is a correct statement.

Option c is the  incorrect statement and hence the correct answer to the question.

So, the correct answer is option c - The receptors of all three interferons belong to the Ig superfamily of receptors and do not lead to downstream phosphorylation events.