Fig. 8
From: Regulatory role of heme oxygenase-1 in silica-induced lung injury
Schematic diagram of the regulatory pathway involved in silica-induced HO-1 expression. Exposure to silica particles produces ROS, which in turn initiates the activation of ERK and ultimately induces HO-1 expression. Silica-derived ROS are scavenged by the heme degradation product bilirubin. Silica-induced ERK activation is attenuated by the heme degradation products CO and bilirubin