“…And the same parameters in 3with (1) have the same meanings, and the biological meanings of the remaining parameters are also described in the lower part of Table 1. The general distribution function considered here allows us to include several special forms of intracellular delays existing in the literatures (e.g., [1,5,22,25,26,36]). More specifically, when the distribution h(r) = δ(r − τ ) is a delta function on τ ≥ 0, where δ(•) stands for the Dirac delta function, model (3) becomes a DDE system with a discrete delay for τ > 0, and for τ = 0 it reduces to the DDE model (1) studied in [26,36] if α 1 = α 2 = ω = m = 0 and σ = 1.…”