Figure 3A shows that DLK1 expression was significantly higher in the MZ-CRC-1 cell line (line 2) compared to the expression observed in TT cell line (line 1). In contrast, no DLK1 expression was detected in the follicular-derived cell lines (lines 3–7), reinforcing its potential pathogenic role in MTC. Moreover, in the MZ-CRC-1 cell line, two isoforms of DLK1 were identified: the full-length isoform (50–55 kDa) and a smaller isoform of approximately 15 kDa. Β-actin (45 kDa) was used as a loading control (Figure 3A). Here, DLK1 is linked to medullary thyroid gland carcinoma.