SALL4 and cancer: Interestingly, the SALL4 expression appears to be selectively enriched in leukemia side-population (SP) cells (defined by low Hoechst 33,342 blue/red fluorescence intensity), −a fraction specifically involved in cancer initiation and drug resistance [66], which supports the SALL4 expression features observed in above clinical cases, and suggests a role of SALL4 in maintaining the leukemia “initiating or stem” cell (LIC/LSC) populations.