ATF6 and infection: Besides, as revealed in Fig. 5, metatarsals from 15-day-old mouse embryos were cultured in the absence (CTR) or presence of Ad-ATF6 (MOI = 50) for 7 days; then, stained with safranin O/fast green and alizarin red/Alcian Blue staining of metatarsals, the result showed that the length of proliferative zone and hypertrophic zone of the Ad-ATF6 infection group was elongated compared with CTR, and the percentage increase of total length and mineralized length of the Ad-ATF6 infection group was also improved compared with CTR.