In addition, as few as 101 ALDHhiCD44+α2β1+ cells isolated from LAPC9 (low PSA-expressing; PSAlow) tumor xenografts generated secondary tumors in castrated mice whereas 104 ALDHlowCD44−α2β1− cells were required for tumor formation, indicating that the ALDHhiCD44+α2β1+ phenotype in a PSAlow cell population is enriched for castration-resistant PCSCs [91]. Here, KLK3 is linked to neoplasm.