This interpretation is consistent with the IHC staining pattern seen in human IPF lung tissue, where SSEA4+/CD44+ MPCs are present at the periphery of the fibroblastic focus; whereas few cells expressing SSEA4 or CD44 are present in the focus core containing procollagen-expressing myofibroblasts (see Figure 1) (7, 8, 14). Here, CD44 is linked to idiopathic pulmonary fibrosis.