DLK1 and prolactin-producing pituitary gland adenoma: Based on the transcriptomic analysis of 172 PitNETs, we suggest a solution as follows: 1) somatotroph adenoma: high PIT1 and high DLK1; 2) lactotroph adenoma: high PIT1 and low DLK1; 3) gonadotroph adenoma: high FSHB and low PIT1/DLK1; and 4) corticotroph adenoma: high TBX19 and low PIT1/DLK1 (Figure 7).