In many instances, it is desirable to express exogenous genes only in certain tissues, and/or at will at certain times, and/or only to a certain degree. However, current gene transfer and exogenous gene expression protocols do not provide adequate means of simultaneously controlling which cells in a heterogeneous population are transformed and when, where, and to what degree the transferred genes are expressed. The invention provides methods for using local heat to control gene expression. The heat shock protein (hsp) gene promoter is recombined with a selected therapeutic gene and expressed in selected cells. Local controlled heating is used to activate the hsp promoter, for example by using focused ultrasound controlled by MRI.