Protein extracts from Arabidopsis and Poinsettia. Protein extracts from leaves (10 μg) or protoplasts (5 μg) were separated by 12% SDS-PAGE followed by Coomassie blue staining. Arrows indicate dominant bands at app. 55 and 26 kilo Dalton (kDa), corresponding to the large subunit of RuBisco and LHC, two highly abundant chloroplastic proteins found in samples of green (gr) Poinsettia leaves as well as in Arabidopsis (Ath) leaves and protoplasts, but not in Poinsettia red leaves or protoplasts. No protein extracts of green Poinsettia protoplasts are shown, since the Poinsettia protoplast isolation method is only suitable for red leaves.