Fig 1: CESA transcript, CESA protein levels and cellulose biosynthesis rates measured in Col-0 and cage1cage2 plants. (a) Expression levels of CESA1, 3 and 6 in 4-day-old etiolated seedlings and CESA4, 7 and 8 in the inflorescence stems analyzed by RT-qPCR (mean ± SE, n = 3 biological replicates, UBQ1 = AT3G52590). (b) Secondary cell wall CESA peptide levels from the first 10 cm of 20-cm long inflorescence stems from Col-0 and the cage1cage2 mutants. Significance is calculated with a two-sided Student's unpaired t-test. *P = 0.05, **P = 0.01 (mean ± SE, n = 4 biological replicates). (c) Total 13C enrichment in 8-day-old Col-0 and cage1cage2 seedlings after 13C-glucose supply. (d) 13C enrichment in crystalline cellulose in 8-day-old Col-0 and cage1cage2 seedlings. 13C enrichment was determined with an elemental analyzer-isotope ratio mass spectrometer and is shown as a percentage of total carbon. The data represents three biological replicates (mean ± SD) of approximately 1000 pooled seedlings per time point. Significance is calculated with a two-sided Student's unpaired t-test. *P = 0.05, **P =0.01.