To further explore this observation, we purified CD44+ PCa cells from LAPC9, LAPC4 and DU145 xenografts, VCaP cultures and, for comparisons, CD133+ cells19 from LAPC4 xenografts and integrin α2β1+ cells21, 25 from DU145 xenografts, and performed quantitative reverse transcription–PCR (qRT–PCR) analysis (Supplementary Table 1) of mature miR-141 levels relative to the corresponding marker-negative populations. The gene discussed is PROM1; the disease is posterior cortical atrophy.