Figure 7i and j demonstrate that treatment of IPF fibroblasts with cell impermeable TG2 inhibitor R281 led to a reduction in p-SMAD3 levels compared to the control IPF fibroblasts, with p-ERK1/2 levels also decreasing in the presence of R281 (Fig. 7k and l). Here, MAPK3 is linked to idiopathic pulmonary fibrosis.