MKI67 and neoplasm: On day 4, xenograft tumour volume was still similar to starting volume (indisulam arm n = 5, 94% ± 48%, Supplementary Fig. 14), and immunofluorescence of xenograft tumours (n = 2 vehicle, n = 2 indisulam) revealed a reduction of RBM39 in the presence of proliferation marker Ki67 i.e. in context of viable tumour.