Four major kallikreins (mK1, mK22, mK9, and mK13) were identified in the mouse submandibular gland (SMG). mK1, a true tissue kallikrein, was used as a protein marker to identify different types of SMG granular convoluted tubule (GCT) cells along with epidermal growth factor (EGF), nerve growth factor (NGF), and renin. Kallikrein mK1 was localized in a very small number (~5%) of GCT cells, which were scattered throughout the GCT, indicating that the majority of GCT cells are mK1-negative. Among mK1-positive cells, particularly strong signals were observed in a small number of narrow cells, recognized as slender granular cells (SG cells, Type IV), in the GCT. After postnatal development of the SMG, GCT cells are no longer uniform based on the bioactive substances (mK1, EGF, NGF, and renin) that they produce and secrete. GCT cells were classified into four subtypes, Types I-IV, and it became clear that these subtypes are complicatedly and reversibly converted by the endocrine hormones 5α-dihydrotestosterone (DHT) and triiodothyronine (T3). Duct segments with similar morphology or hormone dependency were recognized in the sublingual and parotid glands. The presence of duct cells with such characteristics is therefore a common feature of the three major salivary glands of rodents.

中文翻译：

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唾液腺导管细胞亚型之间的可逆转化，可通过产生多种生物活性多肽来确定。

在小鼠下颌下腺（SMG）中鉴定出四种主要激肽释放酶（mK1，mK22，mK9和mK13）。mK1是一种真正的激肽释放酶组织，被用作蛋白质标记物，用于识别不同类型的SMG颗粒状曲折小管（GCT）细胞以及表皮生长因子（EGF），神经生长因子（NGF）和肾素。激肽释放酶mK1定位在极少量（约5％）的GCT细胞中，这些细胞散布在整个GCT中，表明大多数GCT细胞是mK1阴性的。在mK1阳性细胞中，在少数GCT中被识别为细长颗粒细胞（SG细胞，IV型）的狭窄细胞中观察到特别强的信号。SMG产后发育后，GCT细胞不再根据它们产生和分泌的生物活性物质（mK1，EGF，NGF和肾素）而变得均匀。GCT细胞分为四种亚型，即I-IV型，很明显，这些亚型由内分泌激素5α-二氢睾丸激素（DHT）和三碘甲腺嘌呤（T3）复杂且可逆地转化。在舌下和腮腺中识别出具有相似形态或激素依赖性的管道段。因此，具有这种特征的导管细胞的存在是啮齿动物的三个主要唾液腺的共同特征。