E2F2 and idiopathic pulmonary fibrosis: Regardless of the levels of periostin expression, most cell-cycle–related genes behaved the same way as MRC-5 cells: expression of cyclins E2, A2, and B1 in the cyclin family; CDKs 1, 2, and 6 in the CDK family; E2F2 in the E2F family; and B-MYB and FOXM1 was downregulated by periostin silencing in IPF lung fibroblasts as well as in MRC-5 cells (Fig. 5d).