The immortalized acute T lymphocytic leukemic (T-ALL) cell line CEM expresses a subset of mucins (Supplementary Fig. 1a) including CD4317, MUC118, PSGL-1 (CD162)19, MUC24 (CD164)20, and the leukocyte phosphatase CD45 of which all but one isoform contain an N-terminal mucin-like domain21. Here, MUC5AC is linked to acute lymphoblastic leukemia.