The endocrine system plays a crucial role in regulating various physiological processes in the body through the secretion of hormones. One of the primary glands is the pituitary gland, often referred to as the 'master gland.' It controls other endocrine glands and influences growth, metabolism, and reproductive functions. The pituitary gland is divided into two main parts: the anterior pituitary and the posterior pituitary.

Consider the following assertions about hormones secreted by the anterior pituitary:

1. Growth hormone (GH) stimulates growth and cell reproduction.
2. Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to produce thyroid hormones.
3. Adrenocorticotropic hormone (ACTH) promotes adrenal cortex secretion of cortisol.
4. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) regulate reproductive processes.

Based on this information, which hormone directly influences the activity of other endocrine glands?