Fig. 4.

Histopathological findings of Napsin A in hyperplasia or adenomas in F344 rat lungs. A, napsin A expression 12 weeks after treatment with NNK; B, napsin A expression 12 weeks after treatment with DHPN; C, napsin A expression 30 weeks after treatment with NNK and quartz; D, napsin A expression 30 weeks after treatment with DHPN. In proliferative lesions, including hyperplasias, the alveolar walls are strongly positive for napsin A (B and D), whereas in inflammatory lesions, the macrophages in the alveoli are positive for napsin A, although the alveolar walls of the alveoli are less stained (A and C).