To ask whether LICs can sense the acidic BM niche through pH-dependent ASICs, we then examined the mRNA levels of all members of ASICs (ASIC1–ASIC5), which are the main receptors for the proton, in the immunophenotypic Mac-1+c-Kit+ LICs or Lin–IL7R-Sca-1–c-Kit+CD34+CD16/32+ leukemia-associated granulocyte-monocyte progenitor cell (L-GMP) cells (a population more enriched in LICs than Mac-1+c-Kit+ cells; ref. 58) by quantitative RT-PCR (qRT-PCR). Here, CD34 is linked to leukemia.