MRTF-A knockdown partially impairs tumour-promoting effects of MSC on HCT8 xenograft growth in mice. 3 × 106 HCT8 cells were coinjected with or without 7.5 × 105 MSC s.c. in athymic nude mice. (a) Tumour volumes were determined using calliper measurement at day 7 (d7). (b) Mice were killed and the tumours were extracted and weighted after 25 days (d25). One-way ANOVA with Tukey’s multiple comparison test (post-hoc). (c) In vivo acquisition of multispectral images of DsRed-expressing tumours in athymic nude mice on d25. Pictures were taken via 2.2 CRi Maestro in vivo fluorescence imaging system (CRi, Woburn, MA, USA) with Maestro software (2.22). Exemplary grayscale images were overlayed with respective fluorescence images (intensity weighted pseudocolor mode, scale bar displayed beneath).