tSNE ordination of single tumor cells. (a) Projection of tumor cells in the space of 20-mers present in all cells. The 20-mers separate the cells into 3 loose groups, the rightmost of which is dominated by primary cells and the others by metastatic cells. The cluster in the middle is equally represented by primary and metastatic cells from patient T16, suggesting a state of transition. The cluster on the upper right is mostly metastatic with some primary cells. This suggests two distinct stages of advancing tumor cells based on k-mer composition. (b) Projection of cells in the space of only those 20-mers that remain after the differential abundance test for k-mer selection. Cells group into 2 clusters, one of which is entirely composed of primary cells and the other a mix of primary and metastatic cells.