Luminal-restricted clone incorporates into the ductal lumen in vivo and expresses significantly higher luminal-specific markers CK8 and Elf5. (A) The luminal-restricted clone incorporated into the ductal lumen when mixed with primary mammary epithelial cells prior to transplantation. The luminal-restricted cells stained blue upon X-gal staining, since they were derived from CD cells previously engineered to express β-gal. (B) Expression of Elf5 by quantitative real-time polymerase chain reaction is significantly higher in the luminal-restricted clone compared to the remaining progenitor clones. GAPDH, glyceraldehyde 3-phosphate dehydrogenase. (C) Higher percentage of cells in the luminal-restricted clone expressed CK8 compared to the other progenitor clones and nonprogenitor clones 7, 8, 10, and 14. CK8 expression was measured by IF using specific antibody. An average of 500 cells were counted in each group. The x-axis represents the percentage of CK8-positive cells divided by the total number of cells counted. On the y-axis, MP/clone 11 refers to multipotent clone 11 and MP/clone 15 refers to multipotent clone 15.