POU1F1 and acromegaly: These PIT-1/SF-1 positive sPitNETs differ in several aspects from other acromegaly-associated PitNETs lacking SF-1 expression: they are densely granulated adenomas without GNAS mutations, with ectopic GIPR expression, a distinctive DNA methylation profile, and high level of genomic instability [4, 6, 7].