ALDH1A1 and colorectal cancer: Prompted by the observation that PI3KR2 is overexpressed in breast and colon carcinomas, and correlates with PI3K activation and tumor progression [13], we confirmed that PI3KR2 is significantly overexpressed in our panel of ALDEFLUORhigh CCSC samples (Figure 1B), Furthermore, colorectal cancer patients expressing high levels of both the CCSC marker, ALDH1, and PI3KR2 show a reduced survival (Figure 1D).