Different expression of alkaline phosphatase in subclones of human neoplastic salivary duct cell line.

Human neoplastic salivary cell line (HSGc) and its subclones express alkaline phosphatase (AP) which is sensitive to L-phenylalanine but insensitive to L-homoarginine. Electrophoretic analysis demonstrates two distinct bands of AP, one (sb-1) is heat-stable and another (sb-2) is rather heat-labile and faster mobility than sb-1. The AP activity, especially sb-2, shows high level in less-differentiated clone (HSGc-C5) with increased growth rate but low level in nontumorigenic and well-differentiated clone (HSGc-E1) as compared to parent HSGc. This may suggest that the AP is a possible marker for identification of undifferentiated state in HSGc. This study also indicates that dibutyryl cAMP produces an increase of heat-labile AP in these clones.