IL6 and hypertrophy: Additionally, we hypothesized that IL-6 may act in this manner because that cytokine is up-regulated in mouse hearts after 1–2 wk of ISO infusion (42, 43), is actively secreted from cardiac fibroblasts in response to β-adrenergic receptor stimulation or Ang II (19), and is able to directly induce cardiomyocyte hypertrophy (44, 45), and IL-6 KO mice are protected against LV hypertrophy in response to noradrenaline, Ang II, or pressure overload (44, 46, 47).