MAPK3 and neoplasm: On the other hand, animals exposed to HnB smoke showed significant activation of (ERK)1/2 mitogen-activated protein (MAP) kinase pathways involved in Sertoli cell proliferation and normal spermatogenesis (Tommasi et al., 2022), and a marked increase in c-MYC expression as a marker of tumour-promoting potential as reported in smoking models (Dey et al., 2011).