These 3D‐cultured RCC cells exhibited upregulated expression of stem cell markers, including NANOG, NESTIN, TERT, CD24, ALDH1A3, and ALDH1A1, compared to 2D‐rigid‐dish‐cultured control cells (Figure 1B; Figure S1A, Supporting Information). Here, ALDH1A3 is linked to renal cell carcinoma.