[Freedom2specul8]

They've misspelt prolactin. :)

[swarthyguy]

Perhaps it's the Queen's English version.

[aruanan]

They've misspelt prolactin. :)

Perhaps it's the Queen's English version.

Sort of like the guy on FR who insists on the archaic spelling 'insuline'. The -in ending is used to designate a protein. The preferred spelling in OED is "insulin", "protein", and "prolactin".

Oldest use listed in OED:

1932 O. RIDDLE et al. in Proc. Soc. Exper. Biol. & Med. XXIX. 1211 We..have identified this same hormone, which we shall here call ‘Prolactin’ as the hitherto undefined pituitary principle which is essential for lactation in mammals.