CCL28 did not alter α–smooth muscle actin (αSMA) protein levels, IL-6 secretion, or the expression of fibrosis-related genes COL1A1, COL3A1, and FN1 in either normal or IPF primary lung fibroblasts (Supplemental Figure 4, C–F). Here, COL3A1 is linked to idiopathic pulmonary fibrosis.