SOX2 and small cell carcinoma: Small cell carcinoma LuCaP 145.1 in the stem-like grouping expresses stem cell transcription factors (scTFs) such as the core quartet of LIN28A, NANOG, POU5F1, and SOX2, as well as a low level (10-fold less) of β2-microglobulin (B2M) compared to the levels by non-stem cells (19, 39).