Upon exposure to stromal cells, the CD38+SDC1+ myeloma-like clusters enlarged (69%) and the pre-B cell clusters shrank (31%), suggesting that a 4-hour stromal-to-myeloma crosstalk could be sufficient to prime transcriptional changes from the pre-B transcriptional landscape toward the more malignant CD38+SDC1+ one (Fig. 6d). Here, CD38 is linked to plasma cell myeloma.