Fig. 2

Acinar protrusions are independent of composition but depend on stiffness of matrix. A, B, C Matrigel (MG) or collagen I (COL1) gels were thinly coated with collagen IV (COL4) or left uncoated (wo COL4) as indicated. Subsequently MCF10A cells were seeded on top and acinar diameter A and protrusion formation B was analysed 4 days post seeding. C Representative micrographs of acini stained with laminin V (red), actin filaments with phalloidin (green) and cell nuclei with DAPI (blue) on day 4 of acini morphogenesis. Arrowheads indicate protrusions. D, E, F MCF10A cells were seeded on pre-cast acrylamide gels with defined stiffness of 0.2 kPa and 4 kPa coated with Matrigel, respectively. Acini diameter D and average percentage of protruding acini (E) were determined 4, 8 and 14 days post seeding as before. F Representative micrographs of acini on day 4 after seeding on the matrix indicated. Statistical significance was determined by ANOVA using the means of 3 independent experiments, each analysing ≥ 22 acini per condition. G, H Relative mRNA expression of ACTA2 G and VIM H normalised to ALAS and GAPDH. Statistical significance according to an unpaired Student’s t-test (n = 4). *p ≤ 0.05, **p ≤ 0.01. Error bars, SEM. Scale bars, 50 μm