Isolation of cloned Syrian hamster insulinoma cell lines with limited capacity for insulin production.

Cell lines derived from a Syrian hamster insulinoma have been cloned in agar and maintained continuously in culture in vitro for 1 1/2 years. The cell lines have average doubling times of 48 h, they have modal chromosome numbers between 38 and 39, and they retain the ability to form tumors when injected into Syrian hamsters. The cells do not produce immunoreactive insulin when grown in vitro (less than 0.5 ng/mg protein), but do produce immunoreactive insulin when grown in vivo as tumors (mean value from six determinations = 7.1 +/- 1.5 ng/mg protein).