COL5A2 and idiopathic interstitial pneumonia: Conversely, various transcriptome studies of IPF lungs revealed the upregulation of COL1A1 and COL1A2 and of many other collagen genes (e.g., COL3A1, COL5A2, COL6A3, COL14A1, and COL18A1) [12, 13].